Can B&M replace components on Intamin stand-ups? The same engineers worked on both, right? Are the track dimensions the same/are the trains cross-compatible?
I don't see why not, The track dimensions must be very similar if not identical, so if your talking replacement trains, then yes, it's very do-able. As far as the operating component's of the ride? I can't see B&M altering that much from them designing for Intamin to going freelance, so again, very do-able, also don't forget there is a 3rd Intamin stand-up currently awaiting the scrap heap, so there is another source for spare part's.
However, the issue will always be, do the park's want to spend any real money on revamping these dying creatures? Drayton Manor, potentially. La Ronde, No.