I know the Feeling, when a campaign gets too long.
There's so much stuff out there I would love to run my players through, but time is a huge problem, with kids and jobs and other responsibilities.
As I am constantly preparing stuff, having ideas on what to run, writing and reading modules, a Long-running campaign is sometimes too much. Not that I don#t like to run it, but I also want to run and experience NEW STUFF!
That's why I always wished for shorter APs, for example, which run to a maximum Level of 10 or 12. Three issues for one AP would be great for me. Or modules which can be played together, a series!