They kept advertising it as "A Generation's Final Journey Begins".
The undertaking that I remember at the time was that most of us anticipated this would be the last time the entire crew were seen together. Patrick Stewart's paycheque was getting too rich for Paramount (as he was on the up-and-up with the X-Men franchise at the time), so even in the event of a sequel there was a kind of expectation that it wouldn't be the
entire TNG cast, just whatever they could stretch their money towards. Splitting the crew up at the end of NEM still makes this viable, as you might only need to re-employ Stewart, Dorn and Burton, and
maybe McFadden if the deleted scene of her departure to Starfleet Medical was nullified in this hypothetical sequel. Spiner had written himself out, and they weren't obligated to include Frakes or Sirtis anymore, given that they too had been written off.
Chances are they
may have been willing to match Stewart's paycheque for another movie at the expense of dropping nearly all the other regular cast. Whether there was an appetite for that is another matter.