What is behind the FCC plans to abandon Net Neutrality, will that happen, and what will be the consequences for free speech?

We see there being a backlash against this, so this may well be prevented. Time will tell. If this is abandoned it will unleash many negative forces that are greed-based and this will cause a deterioration in service in many ways through distorting access and performance to favor the wealthy, large, service providers and their organization of businesses under their umbrella to the exclusion of independent voices. This is a slippery slope that will begin to erode free speech in a significant way. So this will indeed be a bellwether and is a potential turning point for the worse. Time will tell if this can be avoided.