House Tyrell would probably get some bad times from GRRM. When you get that proud and ambitious you're bound to screw up.
After Dragonstone I'd imagine Loras is less Knight of Flowers and more Knight of Horrors thanks to that oil.
The Florents would be the obvious choice to replace the Tyrells but they're just as ambitious and proud so I wonder who could replace them. As a matter of fact I wonder which houses keep the title lord paramount or who replaces the ones that fall.