I guess one way of looking at it is that the ones with new trademarks issued are the ones worth looking at VS the ones that just had pre-existing trademarks renewed. But even then, a TON of Nintendo franchises were issued new trademarks even the ones that Nintendo is most likely not touching again. And on top of that, most of them were issued those trademarks around the time their previous ones were set to expire.
The most notable examples of this are franchises trademarked around 2008-2010. Nintendo went on a big trademark spree in 2018 and the start of 2020 to have these trademarks updated with new ones and let the old ones expire. These include Punch-Out, Sin & Punishment, Endless Ocean, Style Savvy, Rhythm Heaven, Golden Sun/Golden Sun: Dark Dawn, & Kid Icarus. In that regard, I can't say I believe these trademarks have much to do with anything unless Nintendo is bringing all of these franchises back (even though I believe Golden Sun is coming back regardless of the trademark stuff).
Punchout, Sin & Punishment, Endless Ocean, Style Savvy, Rhythym Heaven, Golden Sun and Kid Icarus are all series that have proven to be big hits at one point in their lifetime. All of these franchises are different genres and would increase the type of gameplay from Nintendo's developers.
And then there's other trademarks that were renewed out of the blue irrespective of any renewal or even an old trademark set to expire. The most notable examples of this being F-Zero, Advance Wars, Elite Beat Agents, Eternal Darkness, Nintendogs, Pilotwings, hell even Disaster: Day of Crisis. It would be strange for Nintendo to trademark all these franchises without having any plans for them especially when they can just renew the trademarks they have in place. None of those franchises were due to have their trademarks expired so it's odd but I also don't believe that all of them are coming back. It's just interesting to note the difference between the above category.
F-Zero, Advance Wars, Elite Beat Agents, Eternal Darkness, Nintendogs, Pilotwings, Disaster: Day of Crisis.
^ These franchises are the ones, besides Nintendogs, that have been out of the lime light for Nintendo consoles for a while. Elite Beat Agents is the only franchise among these that share a similar playstyle to Rhythm Heaven and even still the premise of the games are different.
Eternal Darkness and Disaster: Day of Crisis are the franchises to pay attention to as they contain elements that Nintendo hardly ever touches: Lovecraftin horror and shooter like mechanics (there exists Geist, but it seems Nintendo isn't interested in it).
Even more strange are the ones that outright didn't get a new trademark like Custom Robo. Unlike all the other franchises, CR only has it's pre-existing trademark from the early-2000's in place with no new trademark.
So yeah, sorry for the wall of text but yeah it's very tricky to see which ones are legit and which ones are just for safe-keeping. Still think GS is likely coming back sooner rather than later of course.
I am very concerned for Custom Robo's future due to Nintendo not renewing the franchise. It is among one of Nintendo's cult classics that does something the other series cannot do. A Mech battle arena fighter. That concept has endless potential and would be hectic fun on Nintendo Switch Online.
Hopefully each of these franchises is being revived by Nintendo as increasing popularity of existing franchises only helps Nintendo.
Unfortunately, Magical Starsign, does not seem to be returning which was one of my favorite lesser known Nintendo Franchises.
