Yep. With Cannon Lake being an entirely new architecture being next in line, it will likely use an entirely different LGA format. I was surprised that Coffee Lake was still using 1151.
Coffee Lake is very likely the last line of CPUs to see 1151.
EDIT: That being said, 1151 will still be a viable option for at least a few years, if not more. Sockets don't become obsolete for a good long time (take AM3 as an example, it's only just now phasing out after how long?)