There is an interesting piece on Bisnow about the rise in the US of portfolios of institutionally rented houses ("Single family housing") as opposed to "multi family" (what British investors are starting to look at as Build to Rent/the institutional PRS). 

The article suggests that sensible use of data  can alleviate the poorer economies of scale that arise from having portfolios spread across broad areas and constructed in different ways. 

It is naïve to assume that everything that takes off in the US will also work well here (consider biscuits and gravy) but if tax changes are making life harder for BTL landlords there could be a move towards portfolios of institutionally rented houses. There are lots of individuals who have quietly built up hundreds of units. SDLT would be a sticking point for the companies buying those people out so this might only truly take off following SDLT reform.