You can sue them only for up to six years past. But this is how all patent cases are. This is no worse than any other. No reason for alarm because of that.

I would bet that every one of the companies on the list have been notified and are constantly kept notified so that TPL reserves the right to sue.

I wouldn't be in panic mode. There's still time and I'm sure the law firm is doing what it can to maximize potential damage awards.