The common switch for long haul usually occurs within the same type of aircraft with different configurations such as 74A (new seats) into 744 (old seats) v.v. or 34B (new seats) into 34D (old seats). But with all 747s having already been converted into 74As for quite some time now (same goes for all 343s into 34Bs), this configuration switch debate no longer is an issue at all.

The upcoming winter schedule has already been updated back in August. So what you see Oct 31-Mar 26 should hold up. So for the OP traveling in two months, it is highly unlikely there will be a switch from a three class to a two class metal.

The only high possibility of winter schedule a/c switch I see are some NA flights currently scheduled with the 74A may be replaced with the 77A as more orders for that equipment come in.