This question doesn't even make sense. EVs are already cheaper than ICE cars when it comes to Total Cost of Ownership. There are clear signs that we will soon see EVs that are outright cheaper to buy than ICE, and that replacing a battery will be cheaper than replacing an ICE engine.
This whole EV transition isn't something that's costing Norway money. It's an investment which is already paying huge dividends.
Norway is now building the worlds largest undersea tunnel, and they found that due to the high share of EVs in Norway, they could save 30 million dollars on the project due to decreased requirement for active ventilation. There are lots of examples like this.
The number of car fires in Norway is going down, as EVs are ~10-20 times less likely to catch fire. While each EV fire takes a bit more work to put out, it's not 10-20 more work than an ICE.
Norway can already measure significant decreases in air pollution. What impact do you think that has on the public health insurance expenses?
You should also know that Norway's economy is surprisingly diversified for an oil nation. Norway was fairly wealthy before oil, and will still be wealthy after oil. There are still huge natural resources (hydropower, fishing, etc), a fair amount of industry and manufacturing (Hydro, Yara, ..), a decent tech sector. And after all, a lot of the profits from the fossil fuel extraction has been put into one of the worlds largest sovereign wealth funds, which could be used to help bootstrap more industry in the transition away from oil.