There is no real debate between QSFP-DD and OSFP. OSFP will exist at Google but nearly everyone else is going to use QSFP-DD. The main reason is backwards com

There is no real debate between QSFP-DD and OSFP. OSFP will exist at Google but nearly everyone else is going to use QSFP-DD. The main reason is backwards compatibility for data center upgrades. The only reason to use OSFP might be because you want to use a 400G-ZR plug. But with the advent of 7nm DSP, vendors will be able to fit the ZR into the DD plug. So if the above is true OSFP is not needed now. Honestly, 800G is only incremental at best and frankly it’s not clear that An 800G pluggable is the way to go. The 800G presumes 32 radix and that breaks down power-wise in the datacenter when we get to spine switches where we need 128 radix. The reason being that we need so many power hungry chips to make a high radix switch fully non-blocking (eg Clos topology). 112G SERDES will have limited reach and hence require many retimers which eat power too. So the OSFP is in my view is A solution looking for a problem.