There are no spending estimates for year 2023. A wild guess could be made according to the budgets approved for Q1 2023, but it wouldn’t be anything more than a guess.
I agree with your thought that counting on POOL for treasury runway brings quiet a lot of uncertainty. You can check the following post for some estimates of runway according to the real expenses of Q4 2022: Team Budget Request Analysis Q1-2023.
Specifically, I’m referring to this image (4.2 years of stablecoin runway):
Regarding the possibility of selling POOL to the market or private sellers, that could be discussed in its own separate post. I’m pretty sure it would be an interesting conversation, even more given the fact that I believe that PT Inc. wants to use all treasury funds instead of getting more. Personally, I think we’re currently at a decent position in terms of runway and selling POOL is not needed yet.