As of right now it is still not officially confirmed whether Ascendant, the fourth and final Divergent movie, is still happening, but if The Divergent Series: Allegiant sells well on Home Media, then it will help support Ascendant happening. They are so close to the finish line with only the resolving conclusion left to go; they cannot just leave the movie series at this point without it.
With them cutting Ascendant's budget down, they will be able to return to the same kind of effort and essence that they had with the first Divergent movie, as well as the kind of effort and essence that was put into The Maze Runner movies, all of which were made with a similar kind of lower budget. The lower the budget means that they will be able to focus more on the script and overall content that they are trying to portray, rather than overdoing it with an abundance of CGI and other stylized effects.
The release dates for Allegiant on 4K Blu ray/Blu ray/DVD are as follows:
July 12 2016 - North America July 13 2016 - France July 27 2016 - Australia
It will also be released on OnDemand and Digital HD Media on June 21 2016 in North America
Any country or continent not listed here should have their Home Media formats of the movie released at around the same time or fairly close to/not much farther from those listed.