Yep, the water can be used...but same problem: who will get this water? the rich countries with lots of modern and expensive fuel-cell cars... The countries in need for this water won't have free access to it...

And how do you store it? will we see a water-filter after the particule-filter? ... or will it go into a special tank? Then it will need to be emptied from times to times, especially if you are travelling a lot...

Concerning heavy-duty trucks...
I know Daimler has some fuel-cell busses driving around the world, and I think another carmaker too (a Japanese one, maybe Toyota), so we could see in the future some fuel-cell trucks. Especially if it becomes interesting due to obscene petrol prices.

Anyway, I remember that in China (and other countries), trucks are not allowed to go through the cities during the day because these old motor burn very low-quality diesel and are extremely polluting, and that they are producing enormous toxic clouds...
and as there is not a lot of fuel-stations they are waiting for refuel during hours or even days, with of course the motor still running to move with the others...Burning cheap, sulfur-loaded, extremely toxic diesel...