Jake Sisko
Jake Cisco was a welcomed asset during the days of Star Trek: Deep Space Nine. He was charming, and warm and helped add layers to the story his father, Benjamin Sisko, was featured in. Cirrco Lotton doesn't play Jake Sisko anymore but he's still part of the franchise in some way. He hosts a Star Trek podcast currently and it would be interesting to see how Jake turned out, 30 years after Deep Space Nine ended. Especially, if his impact on the overall narrative is far greater than what we saw as the show ended.
Alexander Rozhenko
The son of Worf is a character with boundless potential. The last we saw of Alexander Rozehenko, was fighting with the Klingons in the Dominion War. Seeing how he turned out and even if he was still with the Klingons would be very interesting. What's more, is that his role in Star Trek could expand greatly. We've heard the fandom for years talk about a Captain Worf series, once that features Alexander's father leading a Starfleet vessel. Yet, with Worf's actor Michael Dorn now in his 70s, it makes more sense to pass the mantel on down to Alexander. Having Worf's son take up a Starfleet ship as captain, with Dorn returning as a recurring character early on in the show's life, would be an interesting dynamic worth putting on Paramount+.