I didn't know ... I haven't setup mine but I would also easily crash that limit.
If I correctly understood the setup you need quite a few chrome apps to use it. The problem is that chrome will cancel its support for these apps in March 2018 I think. That's at least something I read on Ledger Nano Github. So they need a new native app. I'm a bit scared to put all my crypto on something that requires a "new" app :). I had the nano on my wish list because it sounds like a good choice because it already supported so many things.
There are only two apps. Bitcoin/altcoins and then Ethereum. All supported coins use one of these. The hardware wallet needs an app for each specific coin though.
As for being afraid, don’t worry about it. You can move wallets between Ledger, Trezor, and software wallet if you know the seed words.
There is no risk of losing anything if your hardware is lost/stolen or chrome apps no longer supported. I am sure they will have a solution by then. If not then software that supports 24 word seed will be able to recover your wallets.