It will be interesting to see the long term effects of the federal tax reform acted which was enacted in 2018.

There are many of these offered through PPMs and before banking reform, some I've seen had non-recourse loans attached to them.

This is a new provision added by the tax reform. 

Can that happen again, sure, but what is the likelihood of it considering the reforms that were put into place?

As a qualitative criteria, yes, you want your properties to appreciate on some level, but I just don't think you can quantify it well enough to consider during underwriting/ROI analysis.Similar situation with tax benefits - we don't ultimately know what tax brackets will look like long term, and "tax reform" is a campaign talking point every election cycle. 

We’ve been in touch with city council and it’s not a priority for them, although I think eventually there will be some regulatory reform.

If you haven't read about the new laws see here: 13 Things to Know - https://www.nysar.com/docs/default-source/legal/2019-nysar-landlord-amp-tenant-reform---13-things-to-know.pdf?

I recently came across an incredibly interesting White Paper by Robert Hahn arguing for massive reform and decentralization in the real estate sector.

The Trump tax reform indeed changed the rules for deductibility of HELOC as a personal interest, as you correctly pointed out.However, it did not change any rule related to the deductibility of business/investment interest, as @Matt Devincenzo correctly pointed out.

But you also need to know that the whole "science of appraisal" is becoming more and more guesswork and the profession becoming ever more desperately in need of reform as the years go by.