There are a lot of factors. But for most of the world, yes, renewables + storage is cheaper than any other option already:

Unsubsidized Solar Remains Most Cost-Efficient Energy Option in US

With the added costs of energy storage, the LCOE for wind rises to $US45-$133/MWh, which is still much cheaper than coal ($69-$168/MWh) and competitive with combined cycle gas ($45-$108/MWh).

Utility-scale solar, meanwhile, is valued at more than half the cost of coal, at an LCOE of between $29-$92/MWh, average $61/MWh. Large-scale solar with storage ranges in LCOE from between $60/MWh and $210/MWh.

The cost of nuclear power, meanwhile, has doubled since hitting a low of $US95/MWh in 2011, to an average of $US182/MWh, or ranging between $US142/MWh and $US222/MWh, in 2024.

https://reneweconomy.com.au/wind-and-solar-power-half-the-cost-of-coal-and-gas-one-third-the-cost-of-nuclear-says-lazard/

Renewable energy, paired with energy storage and transmission is lower cost than coal, gas, and nuclear energy.

https://energyfactcheck.com.au/2025/01/18/are-renewables-more-expensive-than-coal-gas-and-nuclear/

Las Vegas could get 98% of its power from solar+storage at a price of $104/MWh, which is higher than gas but cheaper than new coal or nuclear.

https://www.volts.wtf/p/solarstorage-is-so-much-farther-along

Even in cold, darker places like Sweden:

Nuclear systems require less flexibility capacity than renewable only systems.

A renewable energy system is cheaper than a nuclear based system.

[However] lower flexibility costs do not offset the high investment costs in nuclear energy.

https://www.sciencedirect.com/science/article/pii/S0306261924010882

In Sweden, where nuclear power generated 41% of the annual electricity supply in 2014, the official goal is 100% renewable electricity production by 2040. Therefore, we investigate the cost of a future low-carbon electricity system without nuclear power for Sweden. ... Our results show that there are no, or only minor, cost benefits to reinvest in nuclear power plants in Sweden once the old ones are decommissioned.

https://arxiv.org/abs/2001.03679

The cost of battery storage projects has declined over 90% since 2010. Solar farms became over 20% cheaper just this year.. Conservative estimates put a further 20-50% drop in prices for various renewables + energy storage solutions over the next 10 years..

The race is over in most the world now, even if you could build a nuclear plant in a day. But given how long nuclear takes to build (still averaging over 6 years, many much longer). It'll be surprising if any nuclear plant started now would be viable anywhere by the time it's up and running.