Shrinking it more would create more of a handicap. Macbook Airs can't run at their default clock speed for very long. Just not enough cooling. Imagine if they shrank this generation of Minis they would be even slower and everybody would be even more pissed.I think this is probably pretty accurate. I've seen other manufacturers that dropped the quad core when Haswell came out. I'm sure Apple could have really fit the quad core if they really wanted but why would they put a ton of engineering effort into an entry level product? I also wonder if they are considering making the mini even smaller with the soldered ram and having only 1 SATA port.
They put dual thunderbolt on the things I think they still want it to be as flexible as possible they just want the revenue from the ram upgrades and a lower entry point so quad cores don't make it this time.