I will definitely add the plot models and support for larger plots, so that you guys doing add-ons can make use of them. I have no timeline though.
One of my concerns is that adding too many plot sizes at once will be confusing and of limited use to the players. For example, let's say I added 4 new plot sizes (3x3, 3x2, 4x4, 4x3), there are currently 7 plot types, so that's 28 new options. More than likely, we'd end up with one or two people adding content to each, so then we end up with situations where a plot type has only a single building plan ever available for it - which as a player, I'd be pretty unhappy about.
Doing the slow roll-out ensures we're all providing content for the same plot sizes so that player's have access to a reasonable amount of content for each.
The 2x2 variation of the Martial plot was my first test run in offering a plot size that I had no content for, and so far, it's getting minimal attention - so I'm being very cautious about a wide rollout of new plot sizes.