It is reasonable to assume that Yahoo will treat their new Tumblr users as they treat their current Yahoo Voices users; in other words, as pieces of garbage. Tumblr users can expect their accounts to be closed willy-nilly and without any legitimate reason whatsoever. And as to the concept of providing any sort of user support, forget it; not going to happen.
And any Tumblr user who dares to publicly complain about Yahoo's practices can expect not only to have their Tumblr account closed, but to have their Yahoo email account shut down as well out of sheer spite. If you have a Yahoo email account, best to transfer your email activities elsewhere as soon as is practical.
The current Tumblr demographic consists mostly of the younger generation. This generation is fairly well known for not taking crap from anybody. As such, Tumblr will probably be a vast wasteland within a couple years.
Here is a BuzzFeed article with more on Yahoo and Tumblr.
And a side note investment tip. Find Tumblr's most direct competitor; sooner or later that direct competitor will start getting a major influx of new users.
|Wasteland ~ Tumblr in Two Years ~ Yahoo Buying Tumblr ~ Tumblr Users Doomed|