I think we will see a slow steady rise in price to over $500 by the halving next year. The price needs to rise to keep mining profitable or a whole lot of mining power needs to get shut down.
At $260 even the SP50 and S7 will be unprofitable at the halving so either new super duper machines that run on nearly no power are coming out or the price will rise.
Regarding the price and the mining you are talking about, it's much more probable that first ones to shut down in case of ~250$ prices after the halving are the older equipement,
making the difficulty drop to a much more profitable rate for s7 and sp50..
But any way you turn it around, there's little chance that price will be anywhere near <300 after the halving.