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.
Out of curiousity, how can a brand name that has gone bankrupt have any commercial value? Beyond the ability to be instant recognised by the public, when people see the name now, they think of how they went bust.
I certainly wouldn't be convinced to book with a company name that had gone under, no matter how much nostalgia i have