Yeah, but by the looks of it, with people on this thread alone already saying that these One Piece DVD sets are a must buy, and judging by how popular the series is among anime fans in general, I have no doubt that they will sell well. That's why I also don't doubt that FUNimation will eventually release a complete season 1 box set. It won't be anytime soon, I'm sure, but I'm patient, and I can wait for it.
Still, even if sales weren't that great, a complete season 1 set would still be possible. I mean, look at Yu Yu Hakusho. If I'm not mistaken, its singles never sold very well at all, yet FUNimation ended up re-releasing the series 14-episode sets anyways (probably because the singles sold so poorly, in the first place). I'm not actually sure how well the 14-episode sets sold, overall, though. However, we all know that FUNimation once again re-released the entire series with those same discs in 28-episode box sets (and without even waiting more than a few months to do so), for just a little bit more than what each individual 14-episode set had cost. So, I really don't see how its not plausible to expect a complete season 1 box set release for One Piece, sometime in the future.