If Phase 5 would deliver the replacement keycaps from their crowdfunded campaign three years ago we'd be able to do these conversions without touching a real 64. I haven't given up hope -- the machinery and molds are being moved to a company that specializes in this kind of low-volume production.
Old micro computers tend to be easy to repair. Given replicas of most retro hardware exists these days I'm generally of the opinion that I'd rather see original retro hardware restored rather than hacked. But ultimately it's not my place to say who can do what to their hardware otherwise - particularly since I'm the kind of guy who also like to hack their own modern devices as well.
Yeah, they are easy to repair, but I think the main point is that they are plentiful. I don't think a few little projects like this are going to put a dent in the overall market supply.
The problem is that is that the demand is already quite high at the moment (retro is cool is seems) and the supply is only finite. Given there are decent enough reproductions I feel it seems a little ill-advised hacking the irreplaceable originals as once they're gone they're gone for good.
Plus if we are completely honest, a refurbished original would also have more longevity than one with a raspberry pi which will have an initial novelty factor but then quickly get forgotten about once the Pi becomes obsolete.
