This could be very interesting option indeed, and somewhat similar to what could happen IRL.
However, it will need a lot of limitations not to abuse it:
- being under 100 A/Cs as you propose seems fair (not too large, nor ridiculously small). 100 in total, including frames leased out.
- someone can't artificially reduce his fleet to go under 100
- having no other base than the current HQ
- former HQ is closed as upon decision, only the new HQ remains
- the need to reschedule all planes makes a strong bank account absolutely necessary (all ops in the former HQ cancelled - no cash until the new routes build up), and makes it a dangerous move
- possible only once in an airline's life
I was thinking initially that the airline could keep its former HQ as secondary base, but I think it would make it too easy: you want it to be daring, starting a new airline with a fair amount of aircrafts but also no income for some time, while the money continues to go out.
Great opportunity, but at greater risks.