Treasury basis trade

I have a couple of questions about the UST basis trade:

1. Is the basic strategy (long basis, hold to delivery or close to delivery) still a profitable strategy on the buy side, or have players gotten more sophisticated (e.g. taking directional views on the basis, etc)?
2. The classic long basis trade seems very easy, requiring virtually zero informational/modeling edge (please correct me if I'm wrong). Why doesn't every single hedge fund get involved? What am I missing?
3. How much of the trade is a view on delivery option fair value, and how much of it is just harvesting the futures premium due to real money demand for UST futures?
4. How does the repo part of the trade work? Is it mostly ON repo's? If so, how do you hedge financing rate risks (e.g. Sept 2019)? If term repo, are they matched to the delivery date of the bond? How much of a premium do dealers charge for that?
5. How much of the trade depends on having good relationships with dealers, and getting good conditions on repo? Is the trade open to any decently sized hedge fund, or does it depend on having massive rates flows (e.g. something open to ExodusPoint, Citadel, and a few others)?
6. Finally, do you see any structural headwinds or tailwinds for the trade in the future? How might regulatory changes impact the profitability of the trade?

Thank you!