Not sure I see the point. They don't use mercury-that's their main advantage over CFLs. But they only last 6000 hours, cost the same as high-end CFLs (i.e. in other words, more than most of the general public is willing to spend), and are still made of breakable glass. As for their claimed color rendering advantage, CFLs could do a lot better than they do with better ballasts and more expensive phosphor BUT the general public has shown they're unwilling to spend the money, even if it means better quality, unless the lamp has a very long lifetime (i.e. 50,000+ hours). Now if they can get the lifetime up substaintially without increasing the cost much, then perhaps I can see these being of interest in the commercial sector. Interesting technology though, sort of like a mini-CRT with only warm-white phosphors.
About the only non-LED technology I might put my money on long-term would be
induction lighting. Induction lighting is more efficient than CFLs and lasts up to 100,000 hours. However, induction lighting seems more suited to the commercial sector owing to its high initial cost and long payback period. The only technologies I see taking over residential lighting long term are LED and OLED. Sure, we may have ESL lamps, CFLs, even IRC incandescent for a while, but long-term none of these technologies seem capable of reaching the lifetime and efficiency numbers LEDs have proven to be capable of. I'd love to be proven wrong of course, but when you look at the numbers things don't seem good for any of the "gas and glass" technologies.
Interesting also how when a disruptive technology like LED comes along, you suddenly have all sorts of innovation in old-school technologies. Reminds me of what I read when diesel locomotives first started appearing in the early 1940s. Steam locomotive technology suddenly incorporated all sorts of innovations (high-pressure boilers, superheating, automated coal feeding to name a few) which until then were deemed "not commercially viable". Steam locomotives reached a pinnacle of performance by the late 1940s. But in the end it didn't save them from extinction. I see the same thing happening now in the lighting world. Still fun to talk about these new developments, however.