It was a terrible missed opportunity that we didn’t get Rommath interacting with Kael’thas in Shadowlands. Rommath has a great backstory, and it’s a shame that it doesn’t really get acknowledged in game.
Meryl could theoretically actually be relevant this expansion, though I don’t have any expectations that he will be. He’s technically a survivor of ancient Arathor, he might remember the Arathi who left and founded the current empire.