The answer to this question is simple, but not quantifiable. There are too many variables when it comes to base assignments. Plus, the likelihood of things of this nature change all the time. It almost doesn’t make sense to think about stuff like this until you’re in a position to submit a base request. The best mindset to have right now is be open minded. If you don’t like the base you get, you don’t have to move there. You can commute to your base from just about anywhere in the world.
Short answer, it depends. Depends on the airline, depends whether the base you desire is senior or not, depends if they’re are and vacancies etc etc. etc. You honestly won’t know until it’s actually happening. The good news is with things moving as fast as they are even if you don’t get your choice immediately it shouldn’t take long until you do.