Your videos are great and have a lot of views because of that, but you have an extrem potential for subs (2kk+)..
If you do more shorter videos more people will subscribe to you because they got your videos recommended two times in a month or so.
You don´t upload very often, and 3 month where you upload pre-produced content on fixed dates regulary could get you into the sub range where it will be your main source of income -> more uploads in the future.
You have a fanbase, extremly high views and extraordinary quality of content, so i don´t think shorter videos will hurt you in the long term - you might make less money in the short term, but i think thats really unlikely as only vids longer than 10 min get the bonus ad money. Go for it and become a Youtube Star !