Maybe if you wanted to swap out games while away, you wouldn't need to wait to get home and dock. The dock could have an internet connection and you'd be able to just transfer the data over the internet. "Swapping" the data on the handheld with the dock on the go.
It'd take some download time, but it could be possible I think.
Likely? Maybe not, but I wouldn't mind it as a potential solution to storage constraints on a handheld system.