As far as I know, DMM appears to be converting all their videos to MPEG DASH format, which will break stream download compatibility. It will take time for them to convert their whole library over, but all signs indicate this is happening. As far as decrypting direct downloads go, provided your not being geo-blocked and you can download your *.dcv file, it should still work. However, due to geo-blocking, many foreign IPs and VPNs are being banned so even obtaining downloads will be difficult.
Of course, this is all strictly speaking for the Patreon release. Hopefully people have backed up most of their libraries ahead of time after being burned by R18.