They do have some ideas, for some, and have some available now.. but not the entire collection. And I don't see an HD remix of Super Mario Bro's #1 coming out ever in the future. Or battletoads for that matter.
Sony knows which games they can remake, launch on something like PS Now, which was/is the testing zone for the future of all digital, all streaming consoles, no more need for hardcore hardware when it will just be a portal through which to play games with an ethernet port and a set of controllers.
Same with Microsoft. They aren't sitting around thinking about ps1 or sega master system roms. Because who cares about the original version of "a boy and his blob". What they think their customers want is ultra 5k high def, pore showing, action packed, across the world multiplayer, shoot everyone and ask questions later type games.
And if they focus on FF1 or the original top down addams family roms, they lose all this time focusing on the games for the younger gen. The older gen, who do not necessarily buy most consoles these days, sit back and play their roms on their phones. They aren't buying consoles like the switch, because they don't have but 10 minute breaks and hour lunches to play, and then go home dog tired to their kids and just fall into bed.