Macports and Sierra vs. High Sierra

[Dave Horsfall]

2nd-hand MacBook Pro (mid-2010), firmware 7,1 with 480GB SSD and 4GB 
memory, Sierra 10.12.6.

I was contemplating upgrading to High Sierra (noting that the dealer said 
that Sierra is recommended for this model, but he could have installed 
High Sierra if I'd wanted it) and I noted that Apple has pulled the Sierra 
installer from the App Store, leaving me stuck with El Capitan (!) as a 
fallback.

I recall that after two previous failed attempts (on an ordinary MacBook, 
late 2009, firmware 6,1) it merely reverted to a saved copy of Sierra, so 
hopefully this will still be the case.

Apparently High Sierra is a massive change, with a different filesystem 
etc.

Anyway, how will this (no installer for Sierra) affect Macports, if at 
all?

Thanks.

-- Dave