Hello Loki!
Unfortunately, I don’t have an definitive answer to your question. However, I believe the legacy navigation menu will be removed from Discourse at some point. The sidebar is the new standard.
It may be very possible that the answer to your question would be “no”, and that the legacy menu won’t benefit from updates anymore.
My suggestion would be to enable the sidebar as soon as possible, but I understand that there can be many reasons why some admins wouldn’t want to do it right now. 
edit: We’ll investigate nonetheless!