So far we've had:
Drop CTRL (TKL)
Drop ALT (65%)
Drop SHIFT (fullsize)
Drop ENTR (80%, but to me this doesn't really count, the name itself is a pun on being entry level)
Is the Drop GUI/CMD next? Maybe as a 40%? The size seems a bit unorthodox from the norm, but the difference between 60% and 65% doesn't seem significant enough to start another flagship-tier product. My guess is that it'll replace the ENTR as an 80%. That being said, I will not feel complete until the last modifier receive its flagship keyboard.
And then the Drop META, SUPER, and HYPER can come next. Looking forward to the space cadet layout, guys!