The age of films only matter when they're popcorn movies like Marvel
Star Wars is timeless... unless it's the ST, which was never in time in the first place.
They also made the RO Tank Trooper Commander.
I'm sure they'll find a way to cameo quite a few of the Rogue One characters in the series, even if they aren't directly interacting with Cassian himself.
Is the show more than one season btw? I'm guessing this one will be. I know the first season is 12 episodes, which is equivalent to 1.5 seasons of Mando.