Lack of Resources? You could test Renee's Warcraft 3 mod, my Warcraft 1 mod and also there was a ship battle map i've seen.
What does this have to do with Blizzard lacking the resources to host the PTR on? They are already hard stretched running the Diablo III PTR as well as the Heroes of the Storm beta, they do not have infinite server resources to throw around.
I have good news for those of you who haven't heard. StarCraft II has been given a "Patch 2.1.9". In this patch, the Warcraft III assets have been released. They are the same assets from the PTR. Congratulations. We may yet continue to use them.