RE:Active cable competitonIt is important to know that Amphenol and many other DAC "competitors" make adapters, cables and assemblies. They don't produce or design chips. They buy the chips from companies like SEV. Companies that you think could be competitors instead are just hardware manufacturers, and in fact may be clients as you I believe you are suggesting. SEV has a number of patents for boosting data rates on cables and therefore will have claims against true competitors if they even really exist.
Recent events seem to suggest that SEV has borrowed to produce chips in mass quantities. Doing so would be reckless unless they are confident the chips are likely to be sold almost immediately upon production (or even prior to).
As a digression, you might ask, "Isn't enforcing patents expensive?" Actually, patent trolls are happy to enforce patents rights on your behalf as long as they keep most of the proceeds. You wouldn't want to give them the whole suite of patents, but rather just the minimum to maintain the monopoly position that patents are supposd to provide and maybe make a few dollars on the side.