They can certainly do that and the average cinema goer won’t notice, nor care.
However, as a fan of Spectre (the awful final act not withstanding) i too am for a continuation of that story.
Sure they can move on with a brief exchange in dialogue to explain Maddy’s absence. But i’d much prefer a YOLT adaptation, with the epilogue of OHMSS as the prologue and inciting incident of Bond25 in the PTS.
I think it’s a shame not to do this when it’s all been set up. Just because they got things wrong in Spectre doesn’t mean that the only way to correct that with Bond25 is to throw the whole storyline out; it’s the easier option, but not imo the right one. In fact having a movie in which they can see what didn’t work is the perfect preparation for a better stab at it now.
They can recast Blofeld if they want - plastic surgery after an escape makes perfect sense, or ignore the face change just as they’d virtually ignore Spectre if Bond25 is a new story.
Personally i’d like to see Waltz back - he’s a fine actor who’s expressed a desire to do it better next time (not that i personally thought he was bad last time - his restrained performance in the cabalistic spectre meeting was perfectly pitched imo). The character he then built was a creepy sadist in the vein of the great Grimm fairy tail villains that Fleming excelled in (just look at the Kiddy Catcher in Chitty Chitty Bang Bang).
Waltz’s Blofeld demonstrated an authentic joy in the pain he inflicts, from the psychological to the physical - wheeling back and forth playfully in his dentist chair while torturing Bond. Another actor may have hammed it up more and made him a cartoon villain. Imo Waltz was just plain creepy and believable.
Sadly for Waltz the added sibling rivalry complicated the character to a point that can’t be adequately fleshed out in the few scenes he had. Without that family baggage playing a major part in his performance he could do even better work as Blofeld next time out.
They should now place the step brother story far in the background. It’s been played out and now needs no more than an allusion or two where it’s pertinent.
What’s more, the end of YOLT (as i’ve bored you all with at length before) provides a fresh and exciting way to intro a brain-washed Bond 7 with the opening 2 chapters of TMWTGG.
EDIT: just seen that you’ve had the same thought:
Absolutely - wonderfully put.