Joss Whedon had allegedly scripted the first episode already. Whedon claimed he and the regular Buffy writing team would still script the series. Giles would remain part of the main Buffy series and other members of the cast have expressed interest in making guest appearances should the project reach fruition. Buffy is not a show I feel I can wrap up neatly with a ribbon. We know after the final frame of whatever episode ends the show that these live will go on, these people will continue to change.
Nothing is frozen in time.
That's the whole point of the show, that we're always changing and growing. Joss also discussed the pitfalls of trying to go big-budget with season four's Initiative concept. So they kept patrolling past the same bush. We wanted to bring a James Bondian world to the show and, quite frankly, it was too expensive. So I don't know if we ever achieved the visual grandeur we needed to get that great government paranoia sort of fun.