The #1 Oh Hell No for anyone contemplating taking a ride in the Titan submersible should have been not having a hatch capable of being opened from the inside. If there was a survivable emergency from which the thing was able to drop ballast and pop to the surface, the occupants could still die from lack of air before rescuers could arrive, hoist it aboard a ship and open it up.
What I'd like to see is someone with the big $$$ buy up all the bits and pieces left over from upgrades to DSV-2 Alvin, DSV-3 Turtle, and DSV-4 Sea Cliff. The original steel pressure spheres for the three were good for at least 6,500 feet. Quite a conservative rating when back in the 1960's it was the test chamber that ruptured nearing 10,000 feet equivalent pressure while the sphere intended to be tested to destruction was unharmed. 'Course that was before each of them had holes cut for 3 portholes, the access hatch, and various feedthroughs for wires and other things. The spheres with equipment inside could hold three people in cramped conditions. For a tourist sub there would need to be less stuff inside and the essentials could be far more compact than the equivalent systems from decades past. Mount all three steel spheres on a single frame and they could be the core of a boat able to go down 5,000 feet with an extreme safety margin. 6 to 8 tourists could be taken along, or that many scientists and researchers could go.
If one wanted to go deeper, get hold of Alvin's second sphere, made of titanium. Turtle still has its second sphere, a later one from Alvin, rated to 10,000 feet working depth. Sea Cliff got the titanium upgrade in 1984 (long after Alvin's in the 1970's.). The US Navy gave DSV-4 to Woods Hole in 1998. They refurbished it and returned it to service in 2002 but has since been cannibalized for parts for Alvin. However, since Alvin's last big rebuild that completed in 2014 removed the last remaining original components (making it a true Ship of Theseus) I'd assume Woods Hole could restore Sea Cliff back to how it was before it became a parts donor.
The current, all new, Alvin was fitted with a larger sphere, with 5 viewports VS the three it and the other two of its sister ships had, which was what necessitated the all new frame. I assume they took advantage of that to make changes and upgrades that had long been wanted but would have been more expensive, impractical, or impossible to do by modifying the 1960's original frame.
Getting hold of Turtle and any still existing parts removed for upgrades would be a tougher deal since its original sphere is in a museum and I assume the boat itself may still be claimed as US Navy property despite being stricken from the US Navy Registry in 1998 and it was on display at Mystic Aquarium in Connecticut. If the Navy officially donated, gave, sold, or otherwise transferred ownership of Turtle, then obtaining it to refurbish and upgrade would be considerably simpler than getting Woods Hole to turn loose of any old parts they still have from Alvin and Sea Cliff.
One of the neatest things I own is a DSV-4 Sea Cliff hat. I dunno if it's some gift shop thing or if it's a hat a crewmember used to own. I picked it up at a thrift shop in Boise, Idaho. If it was a crew hat, is it from its time under USN or Woods Hole ownership? I find it odd that the logo on it has a profile of the Trieste II, DSV-1, instead of a profile of the Alvin class boats.