I am also optimistic about OSFP as compared to the QSFP size for 400G. I'm not a laser engineer but I do have a pretty good understanding of how 400G will be achieved through two strands of singlemode. For medium reach optics it's actually an 8-channel CWDM with prism built into each optic, so the optic body needs to be large enough to dissipate the heat from eight separate 25 Gbps lasers. CFP size will obviously handle that but is a true first generation solution and is huge.

The only bad thing about OSFP is that its highly similar name will confuse the hell out of network engineers who never see the OSI layer 1 of a network, and deal with things at OSI layer 3.

OSFP != OSPF (the routing protocol).