Since Starfleet Academy was greenlit earlier last year, there has been much speculation as to when we can expect the series, who will star in it, and could we see characters from other series even if the series is set in the 32nd century like Star Trek: Discovery. As we all know, time is flexible in Star Trek and can always be worked around, especially when it comes to the legacy characters from the earlier Trek series.
Starfleet Academy will introduce viewers to new cadets trying to make their way through the Academy and into a career in Starfleet, and they should be learning from the best Starfleet has to offer. That would be the greatest captains, engineers, science officers, and communication officers from past and present. And one way to do that would be through the use of holographic teaching.
Star Trek: Prodigy introduced Hologram Captain Janeway as a mentor for the crew of the Protostar, which was easier being that it was an animated series. However, actors from any of the series could make appearances on Starfleet Academy through the use of vidscreens or holograms, much like how we saw Captain Shaw in the final episode of Star Trek: Picard.
Having the cadets learn from some of the greats who have yet to be introduced in the later Star Trek series, like Captain Archer and Captain Harry Kim, would be the perfect way to bring those characters and correct issues in the canon like Harry's Kim lack of promotion. And, in this instance, age would mean nothing as they could already be deceased, but their knowledge would live on.
Perhaps this is something CBS Studios has already considerd. I'd like to think so as it could fill in the gasp in the canon and let valued Star Trek viewers know about what became of some of their favorite characters.