Twitter is far from dying given the restructuring and the current pile of VC cash it's sitting on atm.
Twitter dying is a huge opportunity, they've certainly proven the demand for it. It's a surprise there aren't thousands of VC-backed wannabes popping up already. Would be really interested if FB or Google bought them out and sought to integrate.
At the same time they proved demand they also proved difficulty in monetization. Even if you have better execution there is the large network effect for acquiring/maintaining users.
They have proven sizable, but finite demand. And they have proven that even being as popular as they are, making it work as a business is tricky. It makes very little sense to invest in disrupting a niche where the #1 player has not found financial success.