I'm not going to buy spares unless it's something I like so much that I want to have two copies, and that hasn't happened yet as far as engines are concerned.
I've resigned myself to the inevitable failure of electronic components - at the point where such parts can't be found (which is probably 5-10 years away), I'll just stick an e-unit in, wire the motor directly, and run conventional.
IMO, the bigger risk of availability is related to frames, trucks, and gears due to zinc pest, etc. And this might be mitigated by all of the inoperable engines that will hit the market as the electronics fail.
Another concern is that the cottage industries which supply aftermarket items (like Dallee) will fade away as the owners retire.
