Doubt it for the immediate future.
Those smaller components come at a price premium that doesn't make sense for the mac mini, as the entry level Mac. Moreover, as a desktop/headless mac, the mini doesn't really need to get any smaller. Apple would also have to invest in a complete re-design of the mini: its case, architecture, etc.
If anything, the mac mini case could stand to be slightly larger to accommodate larger harddrives, and make user upgrades easier. That said, I don't see Jobs making any computer have a larger footprint than it's predecessor...esp. something called the mini 🙂