So basically we are where we were before 199A, with sifting through the grey matter when trying to define a trade or business under 162 which doesn't define it clearly itself... but per the Supreme Court in Groetzinger, 480 U.S. 23, 35 (1987), said, “We accept the fact that to be engaged in a trade or business, the taxpayer must be involved in the activity with continuity and regularity and that the taxpayer’s primary purpose for engaging in the activity must be for income or profit.”
So we (Tax Pros) will need to advise our clients on the benefits of taking the 20% QBI compared to the risk from exposure that 20% deduction might create... because many will derive from the above statement that basic landlord duties fall within the definition provided above (collecting rent, qualifying tenants, bookkeeping, etc.) and I'd be hard pressed to disagree with them in a vacuum... but .... the exposure.....
I think my main point is that it is silly for anyone to say that it (rentals) definitively DOES or DOES NOT qualify for the 199A deduction. Let's not cause a stir over this because there is still time for more guidance or technical corrections, etc... and even if that doesn't come down, the answer should always be "it depends" and it's different for each client.
IMHO