So we expected some definition of alpha in a year, did we get it?

We did not. It took about 10 years or so.

Or did the feature creep only just started to gain speed a year after the announcement with the specs getting (some definition of) finished only several years later?

I never realized this until I re-read the link when raiph posted it, but Larry's observation about the time between releases getting longer and longer applies even more so to the Apocalypse documents, which reached 6 or 7 before being replaced with something else. I find that amusing.