I sure hope you are right, but Cuba is not really known as a destroyer of storms. Many have spent considerable time over Cuba, only to quickly resume intensity over the hot water of the gulf. I will hope that Ernesto will somehow travel the entire length of Cuba, from east to west. That might do it.
There are moutains in far SE Cuba that go up to 6,500 feet. That probably wouldn't destroy Ernesto, but would definitely put a damper on him. And if it tracks just a bit further north and east now, that would hopefully keep it out of the Gulf.
The waters between Jamaica and Cuba have the highest hurricane heat potential in the Caribbean. Let's hope it doesn't track through there.