There may be another side to this. As the C150/152 fleets become unaffordable, some cheap flying might become an option as owners get ready to fly them into the ground.
With the deadline date approaching, any unused engine hours would be better flown, than lost to paperwork and a 6,000 Euro bill for looking at what the next bill is going to be.
There will also be a load of engines that don't get slotted into that category and will have hours left. So I'd expect a lot more engine swaps for 500 hours of life than refurbished airframes.