Just a heads up: SDL's use seems to have declined greatly in the last 10 years. Unity and libgdx are more likely to see FOSS games developed for them.
SDL and Unity can't really be compared, and libGDX is for Java. As long as people develop their own engines in C/C++, there will be a demand for SDL. It's not like Unity will be ported to MorphOS, so a complete implementation of SDL2 will be useful to have.
I see the jimmies have been rustled.