I don't think FD will make old ships more stable with sco, it's not commercially viable because then it will be harder to sell early access for arx to new ships, which must be better than the old ones to be of interest
Thing is, all the new ships that we've had (so far, at least)
are better than existing ships in one way or another, regardless of SCO.
The closest thing to a direct equivalent is probably the Python 2 and it says a lot that it
is a viable alternative to the FdL, and a far better choice (IMO) than the Mamba,,, which was
intended to be an alternative to the FdL.
The T8 hauls more than a Python, the Mandalay is just flat-out better than the AspX or Phantom in many ways and the CM5 is so far ahead of every other small ship that they can't even see it from where they are.
If FDev carry on creating ships like these, having an SCO-optimised AspX or Krait isn't likely to deter anybody from buying (with Arx) whatever ships FDev decide to release in the future.
About the only thing that
might be a bit awkward would be if FDev make the Annie, Cutter and Corvette SCO-compatible
without releasing a new large-pad combat ship that has native SCO optimisation first... and creating a new alternative to the Annie/Cutter/Corvette that isn't just stupidly overpowered might be a bit tricky.
I suspect it's an entirely moot point.
I'd bet that a lot of people would
still pay for early access to any new ship that arrived, regardless of it's capabilities.
Honestly, if FDev wanted to, I bet they could apply early access to paintjobs, ship-kits and modules and people would pay for them.
People just like having new toys to play with... especially if they're toys not everybody has.