Just Jason's opinion - I don't think that is a good conclusion to draw... I expect that dashboards will get a gigantic overhaul at some point, which is likely as not to include a back end data path change.
But whatever. We're just guessing / expressing feelings, not facts on that topic. 
There are various apps using websockets - supported or not - so you are likely correct that even if it went away or was supplanted by something else better, it wouldn't happen without notice.
Hubitat has a very good track record of not deprecating used functions (official or not) without notice.
And now I'll let this drop... I don't have time to compare every event between hook and socket and figure out what else (if anything) isn't reported by the socket... But I have to assume if this (as well as event type physical/digital) was missing other things could be too.