The downside to the user experience, so to speak, is that the newer OS will be more powerful / featureful, which will require updating a lot of managed policies for places like schools or locked-down businesses. They'll have to evaluate whether they want to deal with that and continue on the new OS and commit to it in the future, continue with it for a very short time then start all over again on windows or something, or just give up the time they were promised.

Of course, I don't think any schools are getting 10 years out of a chromebook, but some businesses might be.