So, it will be sometime this year that the manga runs out of content to adapt.

Even if this happens I have faith in the TEIS mangaka. The manga adaptation is really well-made, and shows a clear mastery of comedic timing in comic form. If they have to come up with a filler story I have no doubt it would be hilarious. I doubt that’ll happen soon though; even if there isn’t a publicly available volume 7 of the LN surely the writer can send them a draft or outline or something to go off of.