I have not had any need for new rotations just due to the reduced durability (40 and 80 down to 35 and 70).

80->70 Durability just means, literally, one fewer move. From 80 down to 20, or from 70 down to 10, is the same number of moves, and handled the same way. Master's Mend 2, and you're back at full Durability. Then, instead of 80 Durability's 6 moves before having to do a Byregot's Finisher, with 70 Durability you only have 5.

40 Durability vs 35 Durability pretty much has no difference. You cannot do a WN->SH2->5HT rotation, but you can still use one move (CS2 or something) then use SH2->WN->4 moves then restore Durability, either MM1 or Manipulation. The change from 40 Durability down to 35 has had literally zero impact upon my patterns.