Apple will never add DLNA support, because DLNA is a Samsung thing.
Also... I would LOVE to be able to add an external HDD to the USB, but that would discourage the use of iCloud, so we know Apple won't do that, either.
What I would like to see ATV morph into is.. The device we have now, plus:
Cable TV Tuner
Apps
USB, or <even better> Firewire, External HDD & Superdrive Connectivity
Motion Sensitive Games, like "Connect".
<Add to all that a new Superdrive that plays Blu-Rays>
That combination would, or could, make ATV the ONLY device I would need... And my TV would always be on HDMI1.
[Mid '12 Macbook Pro, Mountain Lion, Release Day iPhone 5, ATV 3G]