I'm not in a position to say if this is as bad as the 3rd party rugpull a few years ago, as it may only mean people have to pay Gnip for the same data instead.
To be clear - the only access to the firehose that has been cut off is for people who want to resell that data.
The writing has been on the wall for that for quite a while - there's really no reason for Twitter to sell data to a third-party, who can then sell that data to other people.
End-users of the data are still free to purchase the data from Gnip/Twitter and do whatever they want (within the TOS of Twitter)
Why should Twitter sell data via a 3rd party? Note that DataSift tries to equalize platforms and makes Twitter look like just another option. Right alongside the companies that they have no relationship with (ones where you give them API keys and they connect for you). Datasift was also taking a rather nice cut of the money, and Twitter can easily provide the same service.
Having a third party handle it, take a cut, etc. only make sense if you want to keep customers at a distance (say, to pretend to be concerned about privacy), or if you're too busy or unsure about building the service yourself
Cutting Datasift off (really, just letting the contract expire) is nothing like terminating API access for third parties.
Only Twitter acquired Gnip can keep using it whilst access has been cut for companies like Datasift.
http://www.theregister.co.uk/2015/04/11/twitter_cuts_off_fir...
http://blog.datasift.com/2015/04/11/twitter-ends-its-partner...
https://blog.gnip.com/twitter-data-ecosystem/
I'm not in a position to say if this is as bad as the 3rd party rugpull a few years ago, as it may only mean people have to pay Gnip for the same data instead.
http://blog.datasift.com/2015/04/21/processing-twitter-data-...