By that time whole bitcoins will be moving around the lightning network in one go. So, yeah, still no change in the friction going forward. If the economics of running nodes remains similar against the living costs with an increase in block size then there's that solution too. It is possible that advances in the protocol will drastically reduce the on-chain data size per user as has already happened several times with new transaction formats and segwit and so on.

When all LN nodes support AMP fully larger payments will become easier and more routine on LN.

I doubt that BIP 42 will ever be rescinded. Certainly, from my cold dead hands!