Earlier this year Avid spoke about some big changes coming to Media Composer and one of them is now here as part of Media Composer 2018.7.
The Live Timeline is quite a big change for MC – in the past, when the timeline was playing all you needed to do was breath on a different part of the interface and it would stop. Now you can do a large number of tasks while the timeline carries on playing. Other programs have been doing this in some ways already, including Premiere, Resolve and EDIUS, so it is nice to see this added to Avid and obviously for users of Avid a huge step forward.
Doing more things at once does mean you need more resources so Avid has stop qualifying some older computers as suitable for the Live Timeline, in particular old Mac Pros from 2012ish. This does not mean they will not work, just that Avid is not qualifying them so they may not work, and if not there is no solution.
Scanning the reaction on the Avid forums it may also be the case that, if you have a Blackmagic device for monitoring, this will not work until Blackmagic release updated drivers to work with the Live Timeline. Blackmagic released the 10.11.1 drivers on Monday but I do not think these are the correct ones needed. I have not had a chance to test this personally.
Other changes include the ability to handle 16K timelines (for those times when 4K or 8K are just not enough), support for NewTek NDI video over IP, and high frame rate support (100, 119.88 and 120 fps).
You can read more on the Avid website: http://community.avid.com/forums/t/184920.aspx
The full “what’s new” PDF is available here: http://community.avid.com/cfs-file.ashx/__key/CommunityServer.Components.PostAttachments/00.00.85.98.59/whats-new-8_2D00_2018.7.pdf