I reject the premise.
Twitter isn’t dying because you believe there are fewer users than there used to be — or fewer tweets.
Perhaps that’s just your timeline.
Sure, some people will stop using something because of abuse, and I agree that there is way too much of it on Social Media (well, any is too much, but odd, out-of-character mistakes can be forgiven), because some people take the freedom of being able to post what they like and abuse it — but eventually they come to a place where they are on the receiving end and they learn what it’s like to be the victim.
Like chat rooms and other online social media before it, I make ready use of the block/silence/mute buttons. I’ve long got over wasting time, making a fuss back to such people and deny them the platform to continue any such with me, with an increasing minimum of fuss.
In a way, the fact that there is abuse at least confirms that the platform is truly open to all. It’s what you do with it, that counts.
If you are quitting Twitter because of abuse, as far as I am concerned, you weren’t using it properly or fully in the first place, or lack patience yourself — or had unreasonable expectations of what to expect from the start.
As far as I am concerned, dealing with abuse is easy. Use the block/silence/mute button.