alt Hacker NewsIn the US the average car is 12 years old. I don't know Norway, but I expect similar. Which is to say I don't expect this to have made any difference in the number of gas stations yet. Gas station owners are watching numbers, but and are likely to open less in the future (not zero, some new development/locations will be important, but some locations that previously would have got one will not longer be worth the investment. Or maybe they put in the station without gas pumps - people still need those snacks (again I don't know the market in Norway, in the US that is how it would be).
Gas stations are also trying to figure out how charging fits in. While people are expected to charge at home, there will still me some demand for on the road charging. This is a place that hasn't worked out yet (I personally expect people will go for a nicer meal and sit down for an hour charge - but this might be my bias)
Quick AI search suggests average car age in Norway to be 11.1-11.3 years, so indeed quite similar.
As for what would happen with gas station when EV's dominate, what already seems to be in progress here (not due to EV's, but other factors in the market) is that the "traditional" gas station serving stale coffee, snacks, and windshield wiper fluid are on the way out, replaced by either unmanned cold stations with just the pumps, or then by major roads large full-featured mini shopping malls with groceries, half-decent restaurant (sometimes several), and other shops. I think in a future EV world the cold stations would disappear but the higher end service centers would do fine.