[mhays]

If that's your plan, your city will have to make it clear that after a while, there will be an upzone. If you say that, much of the land will still wait for it. Meanwhile they'll have a good reason, potentially, to do nothing.

Your 3-5 story density is too low if you're really talking about a downtown. Even the future mixed highrise/lowrise district won't be very dense. It would be better for neighborhoods a few blocks away.

Here's an idea that (a) doesn't preclude highrises if someone already wants to build one and (b) might kick-start some lowrise density: Do a tax abatement program (if you don't already have one) or even a partial subsidy, but have it apply only for the first wave of projects and only for housing at certain income levels, maybe 50-120% of median. The subsidy could be justified as workforce housing toward the low end. Also don't require very much parking. Maybe fill a few acres at 100-150/acre.