Planning for the 1990 season was already under way when the show "was placed on hold" in 1989.
It was also going to see the end of the "Cartmel master-plan" regards to the Doctors history, which had started in the last 3 seasons....
It was going to be McCoys last season and was going to regenerate after killing himself after mental torture.... Ace was going to be written out by sent to Gallifrey to join the time lord acedemy.
The names that the prdouction team where looking at for the 8th Doctor where Richard Griffiths and Ian Richardson.....(good choices).
They where also planning to get the show back on Saturday nights, which would have helped rather than being up against Cornation Street mid-week.
If they can get the show to 1993 without cancellation, then expect a massive 30th annivsery.....
so just for fun....
7th Doctor Sysveter McCoy (1987-1990)
8th Doctor Richard Griffiths (1991-1994)
9th Doctor Ian Richardson (1995-1999)
10th Doctor Paul McGann (1999-2003)
11th Doctor Christopher Eccleston (2005)
12th Doctor David Tennenat (2005-2010)
I've seen most of that and thought about it, too, but I think it unlikely that it would go forward straight on. I suspect it would have a longer hiatus, but I think a restart in 1992-3 would be viable, and especially if we posit Russell Davies coming in 12 years earlier....actually, the timing for that would be about right.
I don't think we'd see these gentlemen playing the Doctor in a timeline where we didn't have a 12 year interregnum, that would be a bit unlikely. Different history of the show, different needs. If Davies was starting over only after 3 or 4 year hiatus (yes, I'm already violating my own initial premise), then would he do a regeneration show, and would he cast a transitional Doctor or go straight for 'his' Doctor? Interesting to ponder.
I do tend to agree that if the show went forward by some miracle without stopping, we very well could have seen Ace at the Academy and a Griffiths or Richardson Doctor (but not both...I like Richardson for the part more myself).