How long can you run Linux from a USB stick?

OK... from what I have read, a USB stick is not meant for repeated writing over and over again. It will fail eventually.

How long will it last?
Just for kids logging onto browse and use office apps and not much else?

Not worried about long term storage, they'll just learn to use Google Drive.

EDIT: what USB stick should I get? USB 3.0 I guess - but apart from that, is there any variation in speed? Assuming I need at least 16GB?

EDIT: would it be wiser to run a smaller less GUI version of Linux instead of a heavy one if running off a USB stick?

Thanks.