What could go wrong?
Right now, for landlines at least, carriers can't rate-limit specific types of traffic. Any packet traversing a network is equal to any other. This is good from the perspective of any common user of the network, as long as these network have sufficient bandwidth to handle the traffic.
So yeah, we might have certain classes of traffic (like Netflix / YouTube) that consume a large segment of the bandwidth, but this is a problem for the carrier, and for the consuming of the content (who might or might not have a metered connection).
When the Net Neutrality regulations end, the carriers will be able to craft all sorts of innovative ways of providing "premium" experiences for both companies and people. This will ultimately result in their own enrichment at the cost of the consumer, and severely disadvantage small companies, or individuals that can't afford the "premium" version of the internet.
Ending Net Neutrality will Harm Innovation
They've been hounding the internet for years. No person actually wants the internet to have various "lanes," this is solely the result of the large carriers using money to influence politics. This issue will only be compounded as income inequality continues to grow as a particular phenomenon of our era.
Do what you can, use the internet to speak while you still can, and keep fighting.