Hopefully not, because I was a pretty hardcore DCUC collector while it was a retail brand and I bought most of DC Icons, but I don't have any of those left from either line except for the Icons 7-pack, Icons Harley, Icons Wonder Woman, and Icons Green Arrow (he's tiny).I think initially it's going to be a heavier split with modern than we might expect, if only because Absolute is such a massive success and the demand for the figures is both large and underserved. And obviously characters that appear in modern media are going to get more attention, but Gunn loves using obscure characters in cameo spots, so that might work out for classic fans in the end.
I don't know if DCUC is going to have any bearing on what they do here, but I'm guessing not much from Mattel's end. It's like whenever new Simpsons product gets released and people reference Playmates - these are 20-year-old lines. They're the most ancient of history. If it has any impact on Mattel's character selection, it's going to be indirect: collectors are probably going to campaign most strenuously for figures they don't have in that scale.
The WWE team got caught overthinking a couple times early on. Their first Sgt Slaughter had blue pants because nobody else did it, then it would be years before they released one closer to the style everyone really wanted. There was also Jimmy Snuka with pants and boots instead of his way more recognizable trunks and bare feet and that was it for him, with good reason.