That's not much - $25K per person over 10 years, and with an average income of $70K per person, and something like half of their economy is energy (most if not all social programs are funded from energy production).
If oil were to stop tomorrow, they'd have around 10 years before the money runs out. (Maybe a bit longer since kids don't earn money.) And if they have to replace all the social funding, they'd have even less time.
Norway is relying on slow reduction in demand, and time to transition their economy. Will they have it? It's far from certain. I feel like Norwegians rely too much on this fund to save themselves, rather than transitioning away from oil now.
However, I find it a bit disingenuous to chide Norway which is doing far better than much larger countries like the UK, US or Germany in transitioning to renewables.
I am not worried for Norway (though when the North Atlantic jetbtream shifts they will likely suffer) - I'm far more worried for the poor and marginalized peoples - they will suffer far more.
It's no surprise that thought leaders are worried about climate change impacts. Some will perversely benefit (politicians who are anti-immigration will gain populartiy because climate migrations are clearly defined by US defense dept as a likely result from climate change). Others may benefit by providing mitigating solutions to climate change itself that alter economies.
You really think that's enough to replace the oil sector?
Anyway, they are still extracting oil and probably will continue to do so for a couple decades. That gives them time to grow their wealth fund and gradually transition their economy. They are at a huge advantage compared to other oil exporters.
Additionally social funding in Norway comes from oil - without that funding taxes would have to go up a lot.
Many large oil exporting countries know the good times won't last, and are planning for it.