Personally I'm fine with the 'weeb stuff' as Asriel oh-so-tactfully puts it, and I'm sure the frame setup there would be pretty useful... I just don't have as much of an interest in System. At any rate, Tarvaax raises a good point about System's variety and versatility, something I think CCBS in its purest form still lacks.
If there's to be any future left for Constraction, Lego will have to put serious effort into expanding the catalogue of pieces and possibilities, and blend the lines between 'shell', 'bone' and 'clipon' parts. Also, one of the reasons Slizer engineering/pieces worked so well was the multitude of connection points allowing for a variety of different uses even for pieces only intended for one; so I'd want them to avoid repeating anything like the Uniter torso shells, which only had one socket connection.
Along with that, in terms of the overall set design I feel like a blend of CCBS and older-style technic (slizer engineering, the act of cramming as many functions as possible into as small a space as possible, without sacrificing aesthetics) would be the ideal, following the example of many good MOCs. Unfortunately, it would also likely be pretty expensive, and while Lego's probably in a much better position to foot that cost than they were back in 2000, whether they'll want to is another question entirely, especially given the recent firings over a fairly small business decrease.
TLDR: Slizers was the best Lego line IMO, and Constraction sorely needs a return to the design philosophy of tight function engineering, maximizing potential piece connections, and unique aesthetics that drove those sets. Assuming Constraction is even still a thing at this point.
But I digress.