I could fix my 1965 Fender Strat today, if a "friend" didn't borrow then sell it years ago. :(
I can't fix my Variax 300's as the main pc board is no longer available.
Folks have replace mag pickups on JTV series, just like fixing my 65 strat.
As a normal guitar, the upgrade/maintenance/ normal parts... is the same. Life of that part should be the same also.
When Line 6 non longer makes those rare pc board parts for the model then you have issues.
With the current models, you'll be left with a really nice "normal" guitar for about the same price.
Not like the red Variax 300 paperweight I now have with no PC board available.
Better, next Gen stuff... $ for $ both Brand new : 1965 strat vs 2018 strat, which would you choose?
That also seems part of the question. How much really has changed.
Analog - digital, dip and back to analog circuits are fast enough for most ears.
Think of the quality of a between a song played from tape vs digital recording.
Then your really a good listener and might be able to hear a difference in GEN 3.. 4.. as circuits by default get faster.
You replace a laptop computer with a newer one as software/hardware can do faster and faster things.
I can still fire up a Macintosh Plus from 1980's, but we've come along way from PONG and solitaire on a computer.
In a music world, a G chord has not changed. whether your guitar can make it sound like a banjo or a 65 strat is what Variax brings to our fingertips.
Just got a JTV-59 and will consider buying a backup PC board so I have it, or my grand kid has it when needed to keep this unique guitar 100% functional.