I would not hold my breath for ultrawides to go down in price. The rumors are ACER and ASUS will release 200hz 1440p ultrawides this year, but that may get pushed back to 2018 with their 144hz 4k monitors. Even if they do get released, it would not surprise me if they price them above their current ultrawides creating a new tier and leave pricing the same for the X34.
I have the x34 and it is an excellent monitor. It is great for productivity as mentioned above. It feels like a smaller triple screen setup with no bezels.
But the monitor you selected is one of the best monitors in the world. It would be hard for me to wait for something else if I had the hardware ready to push it.