Probably not for a while. All current construction has finished I think (citation needed, haven't been through in a while) but the current masterplan is in the works.
Waverley really needs a Reading style rebuild to accommodate the increase in pax over the coming decades, which is what the masterplan will aim to do. This won't start for another five years at least, at which point the station will be completely rebuilt over probably a decade, but that should be the last works for a while.
Quick economics lesson. The UK government takes taxes centrally, and redistributes through the Barnet Formula. There are infinite exceptions to this, and infinite exceptions to those exceptions, but in principle, all tax goes through the treasury, and is then gifted to the devolved parliaments.
The Scottish parliament is free to spend that money however they want. At the moment, decarbonisation and transport seems to be high up on that agenda, but it comes out of the same pot as health and road upgrades for example.
After independence, that money will not go through London, and will instead be collected through the Scottish parliament, and it is still up to them to decide how to spend. It might be there is less money to go around, but it's likely that this will still be a priority over things such as nuclear weapons, so it will still be funded.