Here's some more that just occurred to me, and that I don't believe we included in The Games They Will Play. My apologies to anyone else who may have published about this already - I'd link, but haven't seen it.
Suppose a high-priced consultant of some kind produces memos, and/or creates videos embodying the advice. (Nothing fancy, just talking into the camera from one's desk.) Or suppose at least that the business could be done this way.
Might we now, with appropriate structuring, have sales of property (the memos and videos) by a pass-through business that deals in property, rather than the personal service business of consulting? This is not about capital gains treatment (where it's an old issue, and where one would need to meet the holding period requirement to get the long-term rate). It's just to take the thing out of being a personal service business, not one that sells property, for purposes of the pass-through rules.
If the consultant also still communicates his/her conclusions via conversations with the clients, do we need price allocation between the consulting payments and the sale of property?
And here's another, although it's probably more of a stretch. If the consultant works at home, and also rents the home out via AirBnB, might we have a business of making money through use of the home in multiple ways, and hence that uses capital? Again, existing rules address versions of this type of admixture (e.g., the rules limiting home office deductions), but the idea here is different; it's just about changing categories in the pass-through rules.