I created several new & opened previous projects with the new Cakewalk. So far they're all opening & working between the 2 versions which is great. Never was the case in the past.
 
Does anyone happen to know if this feature will remain going forward & kept in future development?
 Just don't want to be surprised & find out it's changed down the line.
(BTW no issues whatsoever installing & working with the new CbB.)

CbB? Try CWBL. 
 

Cakewalk is one word, anyway I prefer altered chords.

BandLab is one word too...

exactly, hence CbB

Cakewalk Flat BandLab? 

Questions about the future are difficult to answer. The old Cakewalk (company) was pretty good about making their  products backward compatible (IOW current product opening older projects). Forward compatibility (older product opening current project format) is another thing as it involves knowing how to handle a feature that has not been added to the software. Usually SONAR would issue a warning and open the project less any feature it did not support. The one exception that I know about are patch points and aux tracks. Any project using this feature may only be opened with CbB or a version of SONAR that supports the feature.

Yep, it's hard to guess. Was hoping Noel might chime in.
I'll probably end up using CbB exclusively in a month or so when the loose ends are tidied up. I've been through every release since 1994 & I can still open all my original projects.
 
It's come along way since then, quite the technical journey in advancements.
 

Bottom line, if you are concerned about the long term ability to open proprietary formats convert them to non-proprietary formats. For audio those formats are MIDI and wav. There is a pretty good chance tools to handle those formats will be around a very long time. Even if project files open in the future, there could be issues with plug-ins so we are back to keeping MIDI and wav files.

I am opening projects from 8.5 with no problem.