There will be no more development. That's clear from the announcement on the Google + page:
As we continue to focus our long-term investments in building incredible photo editing tools for mobile, including Google Photos and Snapseed, we’ve decided to make the Nik Collection desktop suite available for free, so that now anyone can use it.
In other words, "we're going to cream off elements of the desktop suite for Snapseed and Google Photos and stop development". Though given there has been almost no obvious development since Google acquired Nik in 2012 this is hardly a surprise. Google has form here, having previously bought and then killed off the Picasa desktop software.
Short term this is great news - I'm downloading it as I type. Long term, not so good. While the software will continue to work perfectly well for now sooner or later it's going to become outdated, or unusable and we'll have one less choice. Presumably, Google will keep hold of the technology and the patents so there's no chance of someone else picking up the products and continuing development.