As for paying in dollars I think it would put negative pressure on the BTC price. So maybe working towards getting revenue services to accept alternative currency would be a positive move, then money stays in BTC as long as possible not triggering any sell trades. It would also incentivise governments to spend in BTC since they have BTC on hand and it is internationally usable.
But the government will never accept anything but their own currency to pay for taxes because that would undermine the monopolly on money. Maybe at local level its posible, like some USA state that accepts gold and silver to pay for taxes.