I would not look for the US to make any particular special arrangements with the UK. From the trade perspective, the US will continue to be interested in the big EU market, not the (hopelessly bad) post-Brexit UK market.

Furthermore, President T. may think he can negotiate with individual European countries, but his trade envoys will not hold that opinion. The internal workings of the EU are of only peripheral interest to the US.

I would suggest that a likely scenario is that the EU-Russia relationship gradually softens, and the three 21st Century powers are EU+Russia, China+Southeast Asia, and USA+Canada+Mexico.