My guess is that it will probably come on the top tier Decoy for 2020 and be ready to purchase Feb or so next year. Again a guess. It will drive up the cost of the bikes compared to this years. How could it not?
Yes, it will be interesting as I just ordered by Decoy Base. It would be sweet if they let us upgrade for a decent price, then again, the 540 wh battery has been getting great reviews for range.
I asked them this question directly and what they said was the 700w battery would be an option when it comes out and current owners would just pay that optional price and swap the existing 540w battery for the new one.
I run Magura MT7 Calipers and Magura MDR-P 220mm rotors with Shimano Saint Brake Levers (aka "Shirgura"). Best combination of modulation and stopping power I've ever experienced. For pads I run
the Sport (green) on the front and
the Performance (grey) on the rear. Any Shimano Brake lever is compatible with MT5 or MT7 Calipers. You should use Magura Brake Cables and Magura olive/barbs and use Magura Royal Blood Brake fluid.