Public HSR even going out into the sticks gets rapidly surrounded by commercial and residential real estate rent-seekers, and prices quickly (within 10-20 years) arrive close enough to CBD parity to again price out young families. You would need something like a community land trust or transit authority trust that locks up the land and locks in the basis pricing along the rail line about 1-2 km out on either side of the rail, and around a 3-6 km radius around the terminals, with a taxing jurisdiction about double those radii, that gives the families a shot at entry without the same housing pricing dynamics we see now. That trust would have to plan for incremental, systemic densification on a self-funding model based upon the "rent" charged through taxes. Otherwise, the funding for densification evaporates into land developer hands through the years, because it is non-linearly more expensive to densify than spread out, but the energy utilization and efficiency is much lower and higher respectively per capita with densification than spread out. Land developers are valuable, but it is unfair to expect them to behave contrary to their incentives.