Earlier than I thought. Now it's OFFICIAL: Tether used to manipulate price of Bitcoin (link to a 66-pages-study). Listen guys. IF Tether really gets shut down in the coming days or weeks the first reaction would be an extremely huge pump in BTC price (like a "last breath") as people would panic sell their Tethers to buy BTC or any other coin that is paired with USDT, but after that the entire crypto market would collaps tremendously and I'd say over 90% of all blockchain companies would go bankrupt as their coins would go to near zero.
Before a cold shiver does run down your spine let me share my thoughts and speak fully open with you: I personally don't believe a shutdown will take place in the very near future since it shouldn't be in the interest of the elite to jeopardize the whole blockchain ecosystem. It's more likely that Tether become shut down after Circle created its own stablecoin to avert the risk of an ultimate bloodbath. IMO: Tether was created and got integrated in many big exchanges (including Poloniex from Washington who had the most use of it in 2017 beside Bittrex) with the purpose to inflate the market and GAIN ATTENTION to push the blockchain developements forward, because without Tether we wouldn't have seen significant price growth and the situation would be a complete different now. It's not about Bitcoin, it's all about blockchain technology and its exploration & developement and prepering for future currencies since our current system impends to explode for quite some time.
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3195066