Why hope not? I am not going to sit here and do the math, but there is (generic guess) over 2 million, at least, combinations to have. Locking a certain combination of colors, pattern, and emblem is not a problem. It simply allows a guild to know they are unique with there tabard and it cannot be copied.

Likely everyone will rush to get the 'cool' combinations (namely black colorings, wolf and dragon symbols, etc) eventually leaving folks who don't get there quickly no option to have the combination they want. I don't really think combinations should be first come first serve just so a guild feels unique.

Besides, considering the long term, what happens when a guild becomes inactive, or a couple years from now when there are inactive guilds yet more guilds being made/coming that are now locked out of combinations that aren't even being used anymore? It'd just be more work to keep things updated or refreshed so that doesn't happen. On a megaserver in a game that is big (or will get bigger when more content is released and more bugs are fixed, etc) it just doesn't seem like a solid idea.