I think we are getting a little confused here.
Just because they are dropping support, doesn't mean it's not going to work. remember that dropbox as an app is just a gateway, all it is is their developmental support strategy is changing and they see no further need to code for OS 10.4/10.5 PPC based systems. that doesn't mean the app stops working, far from it. this is the same for various different system based applications not just on OS X but windows as well.
remember the windows XP kill off date and what they said about update support and shutting down the repositary for it. well repositary is still open, though no more support is available than last update produced. Windows Activation server is still resident though not actively processing for XP any further.
If however, I've got this wrong, which I admit to a failure rate of (chime) OH BEEP I've just restarted) there you go lol.
I really wouldn't worry. from the sound of this, they're not switching services off, just not coding the app support any further.
ed