well, one could compute an upper bound by saying that paying more than10% of the UXTO value just for fees doesn't make any sense. So, people that owns an amount below 10x the average onchain fees for 1-IN-1-OUT taproot tx will be priced out according to this reasoning. Under a power law sats distribution, this might mean 80% or more of the world. All arbitrary number I know, but this I feel is the biggest practical limit.