thoughts about future seasons?

I'm frankly very hyped for season two of the anime, but it got me thinking about how long it will actually take to adapt all the LN's. Considering that there are already 15 published volumes, and KNH shows no signs of ending soon, it kind of worries me about the sheer amount of source material the anime will have to adapt. S1 adapted 2 volumes, so I'm guessing S2 will adapt another two (or something around that). Assuming the rest of the seasons follow this same pattern, it's probably going to take around 7-8 seasons to adapt the story, (only up till this point!) Obviously, if that actually happens then it doesn't worry me, but what does is the fact that TOHO may just drop the series as a whole, or heavily condense major arcs that play a large role in the story, due to it being too much to adapt. I'm not very aware of TOHO's track record of adapting media and it would help if someone showed some insight on this.