The problem with our current shared team folders is that you need to make a deliberate effort to share something with the team. That means when you want to pull information from the shared space, you're very likely to get an outdated copy. Thanks to 1.) no storage constraints and 2.) deep OS-integration, all files can actually be always up-to-date with Dropbox Infinite. That really sounds cool.
I don't think this solves the problem of taking forever to sync. Nothing has changed there. You are still bound by the same data retrieval and network latencies to get the file stored in a datacenter somewhere to you. That one is a harder problem to crack because it needs a lot of infra investment in expanding your content delivery footprint and replace SSD's with something much faster, like flash.
I already do this because I have to change my selective sync set quite often.
Yes and no. I have about 80 GB in my dropbox. This is no problem on my two workstations or my big laptop. Unfortunately my Macbook Air has a 128 GB drive. That means I keep having to exclude and include folders to be synced to my laptop or it will run out of space. That is a pain in the ass I would love to avoid.