The big problem from my perspective is, after we get into power generating levels with fusion, what then? We still have to turn that power into something usable and the only way we have to do that at present is basically a big steam engine (I mean, I suppose we could do a big Sterling engine rather than steam engine, but still more or less the same thing from the point of view of complexity and expense). Basically, we just have a fission plant where the fission reactor is taken out and replaced with a fusion reactor. The fusion reactor can produce more power from less fuel in theory, but the rest of the plant has to be scaled to whatever the actual heat output is just like it would need to be with a fission reactor. There's also nothing that suggests that the fusion reactor would be any less expensive than a fission reactor. The things it might have going for it are that it can't melt down or probaqbly explode the way a fission reactor can, so that might mean some cost shaved off the containment building. While it would still be very radioactive, it would produce a lot less high-level nuclear waste and would not need cooling ponds. So, generally it would be cleaner and the waste issues would save a little more money. Generally though, it looks like it would be very much on the same order of cost as a fission plant. There's the potential to be slightly cheaper, but chances are that the actual components of a fusion power plant, being considerably more high-tech than the internals of a fission reactor, are going to wear really fast in the high-radiation environment and require frequent replacement, with the upshot probably being that it would be more expensive than a fission reactor for the same amount of power produced. As a thought experiment, replace fission or fusion with a magical sphere that generates heat absolutely for free, no cost for the sphere (or the control dial that lets you turn it up from zero to infinity), no fuel costs, no waste, etc. If you had such a sphere, how much electricity could you actually generate from it and for how much? That would be your baseline for what you could actually do with fission or fusion with current technology. So, basically fusion would just be an incremental improvement over fission, not some huge leap forward.
So, we're struggling to reach and beat break-even with fusion but, even after we do, there's a lot more to do before we get to "too cheap to meter" (which was always a bit silly in the first place because most people's electricity bills are dominated by delivery and other charges rather than the actual cost of electricity). If we can manage fusion and make it roughly as cheap as fission, then I am all for replacing fission with fusion wherever nuclear power is actually practical. I get the feeling though that renewables are going to be eating the lunch of any form of nuclear power plants in most niches unless we get some really amazing leaps forward.