I believe you can roll it over to other companies with lower fees since its no longer sponsored by your employer. Also, you can use the HSA money whenever you like (on health/dental) even though you may not have a HDHP plan anymore. That's why HSA's are so great!
Also, you can just let the money grow in there tax free. I have my HSA in a SP500 index fund so it is keeping up with the market while I don't use it. I would check into investment options and minimums if you haven't already.