I have just signed up for email updates about the new update from Proboards.
I will be receiving an email from them in February, until then I can only tell you all what is already known.

.1 The upgrade will be changing themes, coding templates and plugins.
This means that eventually version five themes, plugins and templates will no longer work in version 6.

.2 There will be a new design on the whole, but posts and content will not be lost.

.3 Version 6 is not yet in the alpha stage, beta testers are already underway and lots of talk about the new software can be found on support.proboards.com

.4 When version 6 is up and running, all forums (on proboards.com and .freeforums.net) will have 18 months to upgrade before being forced into the new software. Think of this like windows 10, we all had time to consider when to install it. So do not panic!

This means all of our themes will be eventually upgraded to work for version six, if that is achievable.
If not, then I guess we will have to crack down and create some v6 themes for ya'll to use.

Until version 6 is available here, all of our V5 themes are accessible via the proboards library but unfortunately at this time, I see no point in updating our themes any further until the new software update takes place. So if you find any problems with our themes, please post in the Fix me forum for help with them.

At the moment I can see no reason why version 5 templates will not work in version six, so this is good news!
If however they do start breaking or not working as they once did, please post in their respective threads in the FIX ME forum and we will get on fixing them up.