My main thought on this topic is that during the controversy over USDT's reserves, which they claimed to be fully stocked with 'real' fiat currency (USD), it emerged that they actually had 'diversified' into holding BTC and other crypto as well to make up their reserves. Since the demand for BTC and it's price volatility are tied in closely to demand on the supply of USDT, it makes sense that many people considered tether's 'backing' of USDT with BTC to be risky.
When BTC goes down in price, so do the prices of a large % of the other coin markets. When this happens, people tend to buy up the stablecoins. So I am wondering what mechanism exists to guarantee that in volatile periods, the system wouldn't run at at loss. This is quite a complicated system and I definitely don't have a clear workflow for it in my mind's eye.
Also, it seems that this whole idea is dependent on using the DHF fund to buy the BTC, which means that the level to which it can scale in that way is limited and might also limit the scope for Hive to fund worker projects.
Ultimately, any idea like this is going to be an experiment, as long as it can be undone at a later date then maybe it's worth a go.