If Oda ended One Piece in a year's time I'd be incredibly pissed off and give up on it entirely, despite all the time and money I've already invested. I mean, really. How insanely rushed would that have to be?
Series probably has another 10 years in it at least, we're a LONG way off from having to think of "all filler, all the time."
Also I suppose it really depends on what happens to the cast in the end. Dragonball had a fairly open ending, OP may go the sailing off into the sunset route, or it may do something a lot more final.