I think you can ”upgrade” the tracks to use three rails so you can handle both track widths. Also there are trains with adjustabe axle widths.
Adjustable-gauge rolling stock has also been ruled out as incompatible with the Finnish climate.
The most (only?) feasible way to do it is to “simply” build entirely new standard-gauge track next to existing track (and then possibly start upgrading the latter too at some point in the future).
When engineers asked should we do the rails same width like in europe or wider, the answer they got from tzar was "Нахуй шире"
literal translation "wider by length of dick, but meaning "why the fuck we need wider"
- В Европе ширина колеи 1435 миллиметров. Нам делать так же или шире? - Нахуй шире, - ответил император.
https://bigthink.com/strange-maps/580-the-legend-of-the-tsar...
Wheels are anyway wearing parts and are to be changed periodically.
BTW, I'm just speculating out loud.