I think there may well be an opportunity out there for a new carrier... but only if you can get the name Thomas Cook.
The name alone is worth a fair bit of money, and commands a fair bit of respect and loyalty. Relaunching under the Thomas Cook brand will give any new carrier a good deal of credibility, and would be a good marketing boost.
Package holidays are still quite popular - Jet2 is doing rather well, and as someone else has said, easyjet are looking to relaunch a package holiday offering too. A newly launched carrier following a similar model to Jet2 may well be successful. There's certainly plenty of spare capacity now, if a new carrier can get in quick before Easyjet/Jet/Ryanair/Virgin expand to fill the gap, then there may well be an opportunity here.
There may also be a demand for a separate retail business too - it's said that 65% of bookings for TCX came online - so that means there were still quite a large number of bookings through the stores. Not everyone is tech savvy, or even airline savvy. There's still demand to sit down with an advisor and talk through the options. Taking on some of the more profitable stores may well be a viable business too.
The only drawback though is the current cost of aircraft leases. With the MAX grounding issue, spare aircraft are in high demand, and leasing costs are high. The parked up TCX aircraft may not be parked for long.
If a good deal can be struck on the aircraft, and the name can be acquired - then I think it may well be worth a shot. Certainly a better investment opportunity than a resurgent WOW air.. and that seems to be happening!