The planet could accommodate an unlimited number of humans living in floating cities and eating insects, seaweed and farmed fish. Solar would provide drinking water and power. But would you want to live like that?
The problem is most want to live on the land and we are polluting our environment to death.
However, whilst some areas might get wetter, other areas might get drier. Changes in climate are not uniform over the entire planet.
but the areas where most people live are the ones likely to suffer drought, IMO.
Fortunately, we have the technology to distribute the water from where the rain falls in excess, to where it doesn't fall, by building dams and long-distance water pipes.
We can't even afford to do that now, and I can't see the west paying to build such in poor areas of the planet.
IMO a major problem in the future will be increased migration from poor areas that can't support their overpopulation to wealthy areas that don't want them. It's already causing major problems and it hasn't even begun to reach crisis numbers.
The best solution, IMO, is to incentivize the areas at risk to lower their birth rate drastically, but I know that ain't going to happen.
Regardless, if Gaia wants us gone we are going. Can't win against nature.