A wise approach. Some instruments can be kept going indefinitely with attention, occasionaly maintenance. There’s very little in a VCS3 or Synthi that can’t be replaced or substituted - same with a Minimoog. However, something like a Yamaha CS may be harder to deal with or remain out of commission for longer while looking for replacement parts.
I still keep my Prophet-5, despite the fact that I wouldn’t dare try to work on/in it myself. However, I live a couple of hours from Mike Metz, a well-respected vintage synth tech. If I didn’t, I doubt I’d have kept it around.
As a (muted) laugh, here’s a list of vintage gear that needs servicing in my studio at the moment:
Minimoog - needs j-wires cleaned, one rocker switch replaced, one rotary switch rewired
ARP 2600 - needs sliders cleaned, one minijack replaced
Roland SH-09 - needs flaky CV input jacks replaced
Yamaha CS-40M - mixer section needs looked at (osc 2 often suddenly changes level)
Roland CR-78 - needs re-capping
ARP Odyssey - needs j-wires cleaned
Another ARP Odyssey - needs complete restoration
PPG Wave 2.2 - needs keyboard rebushed, j-wires and buss wires cleaned and straightened
Linn 9000 - needs new disk drive
ARP Omni II - needs full restoration
That said, with the exception of the Linn, Omni, and one of the Odysseys, all remain playable and currently in use in my studio.
And as smokyfrog points out above, new gear is prone to fail, too - maybe more so. I’ve sent more new gear in for repair than old in the past ten years, and when the new gear fails, it tends to fail in a much bigger way, and often needs to be sent to a service center. However, there is often a warranty in play.