I think things fall into two categories of obsolescence. One is where something simply is never used any more at all, and the other is where it falls out of common usage but is still used occasionally. Vacuum tubes are a great example of the latter. There are still made and used in very limited quantities, mostly by audiophiles who feel they sound better than solid state. Anyway, for the purposes of this thread I'll stick to the former definition, and just because something is obsolete doesn't mean we'll only see it in museums. We still have a few old record players and typewriters even though we'll probably never use them again. Then again, who knows? In a world where electricity is in short supply that old manual typewriter may one day be dusted off and put to use. Anyway, what do I think will become obsolete in the near future (let's say ten years)? Here's my list:
1) Incandescent lamps. They're already obsolete for small (less than ~50 lumens) lighting needs, and have pretty much been obsolete for interior lighting with the improved T5 and T8 tubes of the last decade. Sure, they have persisted for use in home lighting but this is in large part due to a construction industry which has insisted on putting light sockets instead of linear fluorescent fixtures in new construction. In any case, drop-in LED replacements for incandescents with none of the drawbacks of CFLs (and 2 to 3 times greater efficiency) are less than 5 years away. Auto makers are beginning to adopt LEDs even for headlights. It won't be long before Edison's invention has run its course.
2) Spinning disk data storage. As mentioned in the first post, solid state storage is already becoming viable for portable storage needs traditionally filled by spinning disks. As with everything else electronic cost will drop dramatically, capacities will increase many times, and eventually mechanical hard disks will have a run for their money. I'm personally giving this transition the better part of the next decade but eventually the only moving part in your PC will be the cooling fans (maybe). Perhaps lower powered but computationally powerful chips will enable us to get rid of even the fans within ten years.
3) Tape-based data storage. Already obsolete for the home user. My guess is solid state will make it obsolete for data centers within a decade.
4) Cash and checks. The long promised cashless society is almost here. Debit cards are pretty much filling the last remaining niche. Online money transfers also promise to eliminate writing traditional checks (they practically have for many already). Pretty soon all your money will just be a bunch of bits in some data center. I'd personally like to see the concept of money become obsolete in its entirety, but I don't think we'll become that advanced for a few centuries at least.
5) Most paper objects. There will soon be increasing pressure to use less paper, both to save forests and the energy used to manufacture and transport it. Eventually most if not all subscriptions to magazines, newspapers, and catalogs will be electronically fulfilled via online transfers. Affordable ultra-high resolution SED or OLED displays will enable us to read formerly printed matter without the attendant eye strain usually associated with reading on a computer screen. I'm sure books of some kind will still be made, but these will likely be special things like yearbooks, collectible editions, etc. Most run of the mill dime store novels will only be published electronically.
6) Compressor-based cooling. I'll admit that I'm going out on a limb here since commercial solid-state cooling devices haven't improved much in the last 40 years. However, lab developments in the last few years show that we can do much better. It's only a matter of time before we hit on something which can equal or better efficiency of compressor-based refrigeration at similar or lower cost. I think this will happen within a few years. If so, we'll cease to see compressor-based refrigeration before ten years are up.
7) Chemical batteries. Nanotechnology is radically transforming so many disciplines. I give it a decade at most before supercapacitors exceed the energy density of chemical batteries while matching or bettering them in cost. This development will be spurred on because there are so many compelling advantages of supercapacitors over chemical batteries-nearly unlimited cycle life, simple recharging algorithm, nearly instant recharge capability.
8) Internal combustion engines for ground transport. Here again I'm going out on a limb but a combination of improved energy storage via supercapacitors, an increased awareness of the geopolitical, health, and climatic implications of fossil fuel use, and a growing backlash against the oil producing nations will probably mean the end of commercial internal combustion vehicles, at least for ground transportation, before ten years are up. It'll likely take longer to come up with a substitute for air-based transport, but I'd say within 20 to 30 years we'll have one. My bet is on a combination of high-speed rail and maglev, or perhaps fusion-powered airliners (should we finally commercial fusion power generation).
9) Driving your car. I'll admit I'm skeptical of this happening completely within ten years, but I'd say it's a virtual certainly within 20 to 25. The aging population, increased driver distraction, the need to reduce congestion/safely increase running speeds, plus the current economic toll of accidents makes it a given that once the technology comes online driving will be a thing of the past. I'd say within a decade you'll at least have the option of not driving on some new vehicles which is why I added this to the list. Eventually you won't be able to drive, period, at least not on anything but a racing circuit.
10) Most types of retail stores. We're already seeing many businesses fold because they can't compete with online retailers. I think before another decade is out the only retail stores remaining will be those that sell perishable items, items too bulky to conveniently ship, or items which customers prefer to see in person before buying (jewelry comes to mind).
11) Retail checkout. When you shop for groceries or go to Home Depot within a decade all your items will simply be scanned and billed to you electronically without even taking them out of your shopping cart. The days of waiting on a line to pay will thankfully be over.