re: 1) virtually exceptionless norms that bind<<< The reality of subjective exculpability remains.

re: 2) no conscience can legitimate<<< Primacy of conscience still obtains.

re: 3) objective situations of grave habitual sin<<<

The presumption of innocence and explicit bias in favor of one's right to the sacraments trump concerns for scandal, which, juridically, has evidentiary & prudential hurdles set so high that few bishops ever employ such canons. Ironically, though, the rigorists, for some reason, are spectacularly lax vis a vis such legal hurdles! 

re: 4) no intentions or circumstances can transform into a subjectively good or defensible choice<<<

Amoris was recognizing that so many irregular relationships, somehow, bear spiritual fruit & realize unitive values -not because of, but- in spite of objective situations (& that subjective exculpability may obtain).

re: 5) communion given to Catholics in irregular situations<<<

Beyond juridical routes, discernment can determine!