nothing would change.
Interpol has a mere fraction of the data floating in the Shengen system. It has information on every single stolen vehicle in the Eu, every single person of interest for pretty much any offence as well as a lot of stolen goods.
Compared to that Interpol red notices are only for stuff in the millions and people connected to them.
There is a common theme amidst 95% of terrorist incidents in Eu in the last decade - criminal record of the offenders before converting to the hard form of bearded lunacy. You can get that info from Shengen database. You cannot get it from Interpol.