Honestly, I don't see any problem with the novel-continuity.
The Picard-series will be about 20 years after Nemesis.
Nemesis is set in the year 2379, der Picard-series maybe in 2399/2400.
Star Trek 11 was the last movie, that said anything about the main timeline (nothing more than the destruction of Romulus and Spock's disappearance), is set in 2387 - 12 years before the Picard-serie.
I think, all of the newer novels are set in this time-frame: 2379-2387.
The Picard-series might start in 2399, at least 12 years after the novel-timeline. We will see, what Picard will do in THIS time, not what he did in the last 20 years. Yes, they might mention some important events. Why and when did he leave the Enterprise? Did he become an ambassador or something totally different?
I'm sure, they will NOT say: No, there never was a T'Ryssa Chen on the Enterprise. No, there never was a Typhon pact. No, Worf did not become first officer.... All these things will not matter for the Picard-series.
So when the show starts. the authors will have enough time to fill the years 2387-2399, to the point that shows Picard's life in 2399.
Okay, some things can be problematic: Picards marriage with Beverly Crusher, their son, maybe Data's return.... But hey, it's Science fiction

The authors will find ways to explain it. Data could "die" again... Picards & Crusher were married in an alternative timeline, like in All Good Things....
So the jump to Picard's future is so big, that the few information, they will give us about this time, can be worked into the novel-continuity.