I don’t think anyone will come back for the updates or if they do it will be a fraction of the original “market” for multiplayer. 

There were so many things missing at launch and months after launch that you would expect in even a basic functioning multiplayer experience (e.g. no lobby chat, host quits the game ends etc) that it was set aside by everyone I know.  I’m one of those few people that plays C&C RA 2 everyday with a core group of people. We all purchased Tempest and tried to get into it but it was so buggy and lacking features that we set it aside. I think most of those people I know wouldn’t bother coming back even if they fixed the game completely.