Given the current trends, it seems very unlikely that fusion will be even close to competitive with solar or wind by the time it arrives (which is still probably more than 20 years away as a commercial endeavor).
Fusion, in any of its forms, requires some of the highest technology ever produced by mankind. It then exposes these ultra-high-tech wonders to extreme temperatures, and extreme temperature differences, and large amounts of extreme radiation (neutron bombardment), plus corrosion from the extremely fine hydrogen gas. Initial fusion power plants will operate at a very small energy efficiency, and they will need constant maintenance via high-tech robots capable of withstanding the radioactive environment that the neutron bombardment will create all around the reactor. Most pieces of the reactor will probably not last for more than a few months or at best years, due to all of the pressures described before.
Not to mention, the potential for catastrophic failure, though much less than with fission, is still enough to completely destroy the reactor and a good chunk of the plant, if the plasma containment fails. While of course incomparably safer than a fission reactor meltdown, it would still be a massive economic issue.
So commercial fusion, when it does finally arrive (or if), will be extremely expensive, with its only plausible use case as a somewhat reliable base load. Cheap fusion, if it is even possible, is much further away into the future than that - I would confidently bet that cheap fusion will not exist this century, even if ITER or others reach all of their milestones as planned.
It's not that catastrophic failure destroys a good chunk of the plant, it's that any accident in the hot part of the reactor becomes very difficult to repair. So even a relatively minor accident can turn your multibillion dollar investment into junk.
It might be in the long term, but the same can essentially be said for nuclear (fission) power – the materials cost is low (compared to fossil fuels), but due to the extremely high capex needed to build a plant it's considered expensive.
I think the first ~50 years of fusion projects are likely to be very expensive and I'd expect that reputation to stick.
Why should fusion be radically cheaper? It's very complex, has much lower power density than fission, and pushes materials and systems more strongly (power/area through surfaces, for example; neutron flux as well) than fission.
If you claim either fuel cost or waste handling cost, neither of those is a major part of the cost of fission power. Capital cost is, and fusion moves that in the wrong direction.
Fusion is "cheap" if the externalities are priced in. (Of course that's currently a very big if.)
But even then, assuming a version of "fusion tech currently in R&D" realized today, we can probably build a lot of windmills and battery parks for the price of one fusion power plant.
Again, on the long term it seems ideal. (It can be made portable, abundant fuel in the universe, safer than fission, etc.)
Fusion, in any of its forms, requires some of the highest technology ever produced by mankind. It then exposes these ultra-high-tech wonders to extreme temperatures, and extreme temperature differences, and large amounts of extreme radiation (neutron bombardment), plus corrosion from the extremely fine hydrogen gas. Initial fusion power plants will operate at a very small energy efficiency, and they will need constant maintenance via high-tech robots capable of withstanding the radioactive environment that the neutron bombardment will create all around the reactor. Most pieces of the reactor will probably not last for more than a few months or at best years, due to all of the pressures described before.
Not to mention, the potential for catastrophic failure, though much less than with fission, is still enough to completely destroy the reactor and a good chunk of the plant, if the plasma containment fails. While of course incomparably safer than a fission reactor meltdown, it would still be a massive economic issue.
So commercial fusion, when it does finally arrive (or if), will be extremely expensive, with its only plausible use case as a somewhat reliable base load. Cheap fusion, if it is even possible, is much further away into the future than that - I would confidently bet that cheap fusion will not exist this century, even if ITER or others reach all of their milestones as planned.