I don't think hitting MOQ would be a major problem, because almost everybody would love a matching spacebar for standard keyboards.
Hell, I'd take 2 spacebars per set because they are the first thing that get's shiny. If we barely can't hit 2000 pieces, maybe keypop can come to the rescue again
I'd prefer to extend this GB and wait for the spacebars, because starting a separate GB would cause so much extra fees, shipping costs etc. that it isn't really worth it for a couple of spacebars...
I think you should start a one week poll to check if the majority is in favor of getting those spacebars done and if they are ok with extending this GB or not.