Measured accurately?  

I don't think that having tether is a must. Sure, it does exist and some exchanges are allowing their clients to turn their cryptos into tether so that they will have this idea of trading for USD, without actually doing it, and the exchange can't be pressured for money transmitting licenses and all that crap.
On one hand we could simply trade for fiat. Exchanges around the world are doing it anyway by pairing coins with the current value of their local currencies. They don't use usdt and they don't suse USD, yet they are completely fine. On the other we could implement a new, better tether. There's also the third option available that may seem stupid right now but not in the future. Ignore tether and its new versions and build a closed economy based only on cryptocurrencies.

This is really a great idea but it is not easy to do it. Creating a stable crypto for intermediate exchange between crypto types will help stabilize the crypto market but this will reduce the volatility of the market and make sure that it will not be speculators like. But I am very supportive of this idea because it really benefits the whole crypto market, not individuals who want to get more profit from this market.