Understanding containers and codecs
MPEG-4 is not a container specification. It's a suite of specifications. Parts 12 and 14 define containers (MP4). Part 2 defines a video codec, whose encoder implementations are DivX and Xvid. Part 10 defines another video codec AVC a.k.a. H.264.

You can get a list of codecs, which can theoretically be present in a MP4 at http://mp4ra.org/codecs.html

Whether a given muxer/software offers the feature to include a codec in MP4, or whether a given player accepts a codec in a MP4, depends on the software developer. Generally, MPEG-4 Part 2 should be accepted but players can be finicky about the codec tag and may only play the video if they recognize the tag.

HEVC can be muxed in a MP4 and there's no dedicated or new container for it.