Hence why Nemesis bombed and Enterprise was cancelled there weren't enough fans to keep Trek going.
Actually, the lesson of Nemesis and Enterprise is that alienating the fans is bad
. They're potentially a goldmine -- the fandom-powered franchise
goes well beyond TOS merch -- but only the very hardest-core of them will turn out for just anything with the Trek brand slapped on it.
(We probably shouldn't lose sight of the fact that, especially when it's unqualified, the word "fan" can mean different things to different people, and in different contexts.)
If the only criterion for being a fan is to tune into a show regularly, then it's tautological to say that alienating its fans is bad for show. I think it's a good point that when your steady audience is small and dwindling, as ENT's was, your regular viewers aren't enough to keep things going. Attracting new blood to your viewership is key.
Recapturing the TNG audience was something that ENT repeatedly tried to do but failed at. Ergo, especially in hindsight, it shouldn't have attempted to do that at all, at least not in the way it did. What it should have tried was something completely different, in an effort to attract new fans that were never regular viewers of TNG and/or to appeal to TNG's fans without boring the fuck out of them with things they'd basically already seen.