The constitution and Sharia law are as compatible as oil and water. Actually, even less so. The foundational beliefs upon which is built are 180 degrees from one another.
There is plenty of pontification that con go on to ‘splain it (as the article does), but that is the bottom line.
I large muslim population population, once it reaches a certain critical mass, will result in civil war. Plain and simple. I mean actual bloodshed.
It will also almost certainly dwarf the original civil war. I do know that, in the original CW there were not a lot of religious zealots going around beheading people and otherwise mangling in the name of allah. Next time it will be very different.