That's not how it works friend. The 900e does not have the hardware chip to support DV HDR, and never will. If you want HDR10 and DV HDR support with a 2017 Sony model, you need to get a 930e(Awesome TV btw) or higher 2017 Sony TV. If you can wait until spring, Sony's 2018 equivalent to the mid-tier 900e(900F 2018 model) will have said X1 chip for DV HDR support.
I was looking for a bit more future proofing, and coughed up the extra $200 dollars on a 930e for the DV support on my ATV 4K. Plus the If you really care about HDR, the 930e Peak and sustainable brightness is better than the 900e(Which is still pretty good).
I bought the TV a few weeks before ATV unveiling... so I don't see the need to upgrade. Also, Another poster mentioned what you said already. Futhermore, as an article on the 900E v 930E said, DV support is a nice to have, but not a complete must at this point if you are coming from regular 1080p (or worse) TVs which is my case.
I come from a 32" 720p non-Smart Samsung TV from 2009. So I won't miss what I never had in the first place. I am sure it will look better, but using HDR10 should be good enough for next few years. Also, I don't plan on spending $900ish (give or take a few $100) on a new TV when I just bought a TV.