re: LTE There are several issues. Space, battery life, heat, and really basic hardware compatibility. LTE is not yet compatible with Tegra 3, and having just enough knowledge of hardware to be dangerous I would assume this means that to package them together you need some kind of bus which adds space, heat, and power drain. I could be wrong and there may not be a way to get them to play nice at all.
There is also the idea that the apps market is trailing the hardware market by a good year or more, and that multi-tasking through quad-core is probably not going to be show a huge improvement for at least half the life of your next contract. Jelly Bean will likely release with the Nexus Tablet that will likely be announced at the end of the month. From there it will take them some time to translate Jelly Bean into the next (Key Lime Pie?) phone version of Android (or they will tweak Jelly Bean to that).
My guess is honestly, the first phone that will really optimize quad cores properly will be the next Nexus, which probably won't even be announced for a year. Although I guess they could surprise us.