Short update for those that read the original blog post: it turns out that the answer to the question “Is it possible to run VMware NSX on redundantly-connected hosts in a pure L3 data center fabric?” is still NO.
VTEPs from different ESXi hosts can be in different subnets, but while a single ESXi host might have multiple VTEPs, the only supported way to use them is to put them in the same subnet. I removed the original blog post.
A huge thank you to everyone who pushed me with their comments and emails to find the correct answer.
We migrated our blog a few days ago, and the commenting functionality is not there yet. In the meantime please find our content on LinkedIn and comment there.