It was known from the start that the PoW phase is just a temporary development phase, with no parameters set in stone. Eth2 has a deterministic inflation schedule that depends on total amount of stake.

  def calc_annual_reward(total_staked_eth):
     return math.exp(31556926 / 384 * 64 / 31622 / total_staked_eth ** 0.5) - 1

This is the return rate for validators - this should be multiplied by the average online percentage, eg. 0.9 if average participation is 90%. On top of that comes fee burning, which is inherently variable, but likely to lead to deflation at least initially. Extrapolating fees from the last 24 hours and assuming 10M eth is staked, the net result is a deflation of 1.3%.