Those threats are called "laws". We strive to the ideal of living in a society that respects laws. Twitter/X is free to leave if they don't like it, of course.
Basically it's a discovery process before a litigation. I'm 99.99% sure it won't end up in a lawsuit.
My bet is that the probe will end up saying: 'criminal intent can't be proven'. Then either the parquet (basically DOJ but less political) or customer protection will say "this probe showed that your algorithm wasn't neutral, you choose which content to show and which not show, you're a publisher now" and Twitter will have to prove it's not, or be treated as a publisher.
Nothing.
There is an investigation (there are named offenses that are the main, but not stated as exclusive, focus), not an accusation against X and various individuals.
The investigation may, depending on what it finds, result in accusations against some or all of the people on whom the investigation is focused, but whether it will and what the accusations will be is not known until the investigation has occurred.