There really is no other option other than Undulation for M+. Yes, these changes should be an amazing buff in M+ for Rsham. Part of the problem is they are useless outside of CDs (ascendance mainly). With these changes you should be able to more reliably do cleave healing (chain was already used a lot because of Flash Flood). From a Keystone stand point, yes they will be better. Resto Shaman can already do high keys, of course. The problem is that they have a way harder time than any other healing class at the same gear/skill level.