Renewable technologies (including storage) that are being installed could power the world. The only question is how much they would cost, and how much costs will decline as the world invests tens of trillions of dollars in the conversion, driving the technologies down their experience curves.
Current commercially available nuclear technology, on the other hand, cannot power the world. Thermal reactors use uranium too inefficiently. Either new seawater U extraction will have to be matured (it's not ready yet), or breeder reactors will have to be matured (they are also not ready yet). Both of these would raise costs of the current nuclear system at current uranium prices.
Renewables, at least, have large and growing markets driving the learning and cost reduction, and ditto for storage. Those nuclear technologies do not.
In either case fossil fuels have to be penalized sufficiently to keep them in the ground or (and perhaps this will happen) to force CO2 capture to make them greenhouse safe too (but watch the methane leakage).