Expect a southern rebellion led by the displaced gentry, even after Bosworth Richard will remain unpopular in the South. Actually I have the brief outline of a TL with this POD which sees Richard deal with the remaining Lancastrian commanders before facing a real threat in 'Edward V' a pretender similar to Perkin Warbeck/Lambert Simnel from OTL, supported by the remaining Woodville faction and those 'Edwardian Yorkists'.
As for the effect on history, I read a book of the Battle of Stoke recently where the author states that had the house of York won, it is still likely for the smaller monastries to be dissolved (the larger ones could survive without a Henry VIII type figure) and suggests that the 'Middle Ages' or the period of baronial authority would have lasted longer, as Henry VII was successful in limiting the power of his nobility through bonds, restrictions and fines.