I think it would depend on the creatives.
I also think it would be best if the 1985 line focused on characters and teams that had their iconic versions at the time.
Matter of fact, I’d rather see a ‘DC Icons’ line that had stories for characters and teams set in their iconic era and settings.
A Wolfman/Perez Titans in the ‘80s, a Batman in his Miller ‘Year One’ setting, Wonder Woman in her Perez setting, the Legion could alternate between the ‘60s version and the ‘80s Levitz version, a Satellite JLA series, a classic JLI series...
The important thing would be the continuity would only matter within the book itself.
And a creator could pick and choose what era they wanted to add to.
It would be like 'real' book publishing. Gasp.
Kinda like if Sherlock Holmes was one of DC’s characters, writers would want to write stories set in the Victorian setting with the established characters.
And more readers would probably pick a classic setting Sherlock Holmes story over a ‘unique take’ on the character if they were wanting to read one of his books.