The Kelvin books were cancelled because of behind-the-scenes issues involving overall company strategies and priorities and unrelated to the specific contents of the books. And those issues evidently no longer apply, since two of the books are now coming out
I thought I read somewhere once from one of the PTB's that they were concerned about the future movie's content though. I wish I could remember where I saw that. But I remember reading something, I believe on trekmovie.com around the time they were pulled, that they were in the midst of writing the next movie (STID I believe) and they wanted to see what that movie included before releasing the books. Now, I know that never mattered before but that doesn't mean it couldn't come up as an issue at some point. It was a different regime after all. In fact, I thought I saw that it was Bad Robot or someone with the production company that asked for them to be pulled. NOW, I'll grant that perhaps where I read that and the sources it came from was incorrect, or misinterpreted something. But I don't think this was just blind fan speculation. I think it was based on some article or interview around that time (even if that was incorrect info).
But I've also heard it had some licensing/legal issues with Bad Robot also? I mean, you'd think that wouldn't be an issue, but I suppose something could have come up after the books were commissioned. I mean, no one's perfect and maybe someone forgot to cross a t or something. Didn't that have to be resolved with the most recent S&S contract in fact?
Three or four years should be plenty of room for many adventures. Have you seen how many novels and comics are set during the famous five year mission? It's an endless 5YM, it just goes on and on!
Ha-ha, so true. Among just the novels there are probably enough 5 YM stories to fit a 50 Year Mission.
I would be more interested in novels between ''TFF'' and ''TUC'' with a more matured crew
Yeah, that's a constant gripe, er, request of mine. While the comic books have explored this era a great deal, there are only a handful of novels that take place during this period. I'd love to see some pre-Sulu leaving for the Excelsior and some post-Sulu leaving for the Excelsior stories (if you use Forged in Fire he left the Enterprise late 2289).
I was really excited when Greg Cox's "Foul Deeds Will Rise" novel came out since it took place during that period. It sounds like the authors prefer 5YM stories though, and only write a movie era book when the story they want to tell makes more sense in that time period. I think Greg Cox mentioned once one reason FDWR took place after TFF was because of the age he needed Lenore Karidian to be. There was an E-book that took place in that period as well---"Miasma" I believe.
Personally I love 'lost era' type books, both the literal series and just uncovered eras in Star Trek history in general. Another series I'd love to see continued would the the "Stargazer" series. There is what, over 20 years between "Maker" the last Stargazer book to date and Christopher's "The Buried Age" which takes place after the loss of the Stargazer. I'd love to see someone pick up on that. We never even got to really see Jack Crusher in the novels in any Stargazer books. He had not yet joined the ship when the last book was written and he was dead before the loss of the Stargazer. Esp. with the new Picard show coming out it would be interesting to see more about Picard's early career and life.
. And while his "Captain's Oath" is not totally consistent with Friedman's "My Brother's Keeper" from a story standpoint, they both had a similar, er, interpretation I guess you'd call it about Kirk's earlier career (to the point I can almost see them in the same narrative universe--at least where they aren't directly inconsistent), I think he would be a good choice to continue the story Friedman started. 
But any author will do. 
