It's primary competitor in most nations is coal and natural gas. In the US, it is increasingly natural gas.
Existing plants are not closing because of new renewables but because gas has driven prices down
Reliability is a system-level characteristic. You can design systems with high levels predictable variable energy resources that are as reliable as high levels of dispatchable
Right now it is cheaper, more flexible, and less risky.
Its also silly because there are near equivalent subsidies for new nuclear facilities. They just aren't used because no one can build/finance a new nuclear plant
The wind PTC might allow negative bids but if they set marginal prices, prices should be zero or less anyways. The few hours that happens won't make a difference in profitability
Other than China coal is on the way out. In the US it is in a death spiral and no longer baseload. I doubt much of the fleet makes it past 2030
Rate-based utility ownership of a vendor design is no longer viable. Its also a factor in cost overruns (vendor doesn't care)