I can't imagine why you insist on pointing out the "clear cutting" for wind and solar. Any of the wind or solar installations I've personally seen have required precisely zero clear cutting.
This image shows the estimated land area required in North Africa to generate enough power for the world, the EU or for Germany. Zero clear cutting.
It will require some transmission hardware, but we know how to do that already. HVDC, remember?
https://en.wikipedia.org/wiki/Desertec
Just as an aside, all environmentalist agree that wind and solar farms need to be clear cut and will destroy the environment, regardless of where they are built. This includes desserts. Anyway, ...
Aside from the extremely large geopolitical issues that would certainly arise and the history of instability of the region, at first glance it looks cautiously optimistic. I also like the fact that the Sahara is not populated with that many animals, meaning less habitats will be destroyed along with plant life.
However, I am very skeptical of those land masses you highlight being so small. I have yet to see any calculations that show land masses even remotely as small as those by any physicists looking into wind/solar. On top of this, you will still only get production 33% of the time, just like with other projects in other desserts, albeit maybe more concentrated. Although the Wiki post does not directly say this, they do mention, indirectly, the sunlight is present only about 9 to 10 hours of the day, and that is about a 1/3 of the time.
Additionally your Wki post does point out some pretty serious obstacles that would need to be overcome at the bottom.
First, the cost of cabling over such large distances and maintaining them would be extremely expensive and could effectively offset any of the cost saving with building there.
Second, Europe would just go from being political dependent on the Middle East to being so on North Africa. This would not just be with the country that is producing the energy but as with every single country that the cables run through as well. Anyone of them could hold Europe hostage by threatening to shut off the power. This, obviously, would create a serious military issue as well. On top of this, you would absolutely be dependent on these countries and could not easily change alliances since the cables would run through them and not be easily rerouted. This is different then today since you can more easily change from which country you buy fuels from.
Third, there is simply not enough water available in the region for construction, maintenance and cleaning, and cooling of the panels and turbines. All of this water will need to be imported, adding the cost of the project. Although there is some hope in developing cells where dirt and sand can not attached themselves to the surfaces, these are still in their infancy. Additionally, dry cooling is an option but more expensive.
Last, who will actually own the project? Will Africans be okay with Europeans building this in their country and maintaining ownership and operation? Or will Europeans be okay with footing the bill for a huge project like this only to let Africans to assume ownership and operations? This would be quite the tricky treaty to work out. Also, again due to the instability and frequent regime changes in that area, you would need to be ready to make unpredicted alterations to this treaty after it is in effect.
I would also add, the instability of the region and the fact that, pretty much without warning, either the plant itself could be shut down or cables cut due to coups or wars would make this project very risky.
This is not to say it cant work, just that there are a lot of issues to consider, many of which have nothing to due to energy production nor are inherently stable/reliable.