I'd like to at least see these Pokémon get Megas or anything else special to go with the Sun/Moon theme. I'd also like to see something special done with Espeon/Umbreon and even Vileplume/Bellossom, as they are both supposed to be sun/moon, day/night duos.
In fact, in general, it would be pretty neat for SM to introduce Megas for all evolutions that are obtained with either the Sun or Moon Stones:
Sun Stone: Bellossom, Sunflora, Whimsicott, Lilligant, Heliolisk
Moon Stone: Nidoqueen, Nidoking, Clefable, Wigglytuff, Delcatty, Musharna
The Sun Stone Megas could be exclusive to Sun, while the Moon Stone Megas could be exclusive to Moon. ^^
That's actually what I was thinking! I doubt they'll play a significant enough role to be the game's mascots, but maybe in these games they'll have some sort of hidden power that's necessary to unlock at some point in the game. Or maybe they'll even have some relationship to the mascot legendaries, like perhaps they're the key to unlocking the legendaries' power, or something like that? Solrock and Lunatone's Dex entries say they're from space, so that leaves the door wide open for new possibilities with these Pokémon!
I'm not really sure what Mega Evolutions would do for them in terms of redemption (and I think other Pokemon are currently in need of it more, but that's an aside thought); Solrock's and Lunatone's stats and movesets look kind of wonky... Solrock is physically oriented (but is pretty much a floating rock blob that can't punch, kick, or scratch anything {XD}), so it can't make much use of its thematic Fire-type moves, thematic Solar Beam, and its specially-associated Psychic type, and is arguably deficient in decent physical moves... And while Lunatone is specially oriented, it can't make too much use of its physically-associated Rock type (although I guess there's Ancient Power).. Both of them need Levitate to avoid a Ground-type weakness (not to mention that Levitate is sort of a thematic Ability).. Their base stats could benefit from the buffing, though..
I'd find it weird if they centered a main series game on two Pokemon that were released over ten years ago.