That'd be too bad. And I fail to see the benefit for Seafile Ltd. It's not like the pro version of the server, which is a business model I perfectly understand. Here, the seadrive client is a freeware anyway, and available even for CE servers. Opensourcing it would allow not only the community to enhance it, but more important, the community to package it. I'm lucky right now that the CentOS RPM works on Fedora, but there's no guarante it'll in the future. And if I'm not confident I'll be able to use seadrive in the future, I can't convince my company, or my clients to use seafile as their main data store.
There're also tons of Linux distro which can't use it right now.