I’d worry about lack of buses more than travel on them being free, as above. I agree that once services decline below a certain point people can’t rely on them and then there’s evidence they’re not being used ana a justification to cut. Buses are frequent in London and well used but there’s the population density that just doesn’t exist in rural areas.
My (wealthy) parents love their free travel and they could easily afford to pay. But they’d be mighty pissed off to lose that perk and yes they vote in all elections (as do I actually).
I can’t worry about whether I’ll get free travel in 30 years though when there’s so much more to worry about now and in the middle distance.