Neither now has an impact on upgrades from London, SPMLs may still have an impact on the return to London.

Pre-selection meals were never a problem here, since the reason you would be upgraded would largely be because someone in WT needs your seat. They would theoretically still have access to your meal, which in any case would feature in the general pool of meal options loaded, and complaints would be unlikely. Whereas upgrading someone and giving them an SPML could have been awkward. But there are apparently enough SPMLs in the system now that it shouldn't make a difference, they can change things at the last moment.