· Waste management is easier since our waste will be ~5x less mass per kg fuel (~500x less mass per kWh energy), and also returns to natural radioactivity much faster (one or two centuries). We actually plan to sell most of the fission products as useful materials.
· As of now, our reactors are planned to be mostly stainless steel. Most of the lifetime mass-throughput of current GI-GIII fission plants is concrete and steel, of which we have basically none of the concrete and much less steel because no pressure vessel. So, decommissioning is much easier and probably will be internally profitable.
You're right about the last part, because solar will almost definitely get at least 2x cheaper than it is today, and within not more than a few decades.
My perception is biased (ofc), but in my view it's actually very likely that we will reach or surpass our goal, though, so I personally wouldn't bet on renewables.