*edit: I realized I rambled on QUITE a while, so skip to the bottom for my on target contribution to this thread LOL!*
The A7iii will probably spell the end for Canon cameras for me now. I have had an A6500 for about 7 months now, and no native Sony lenses yet. I have a Metabones Ultra speed booster so all of my Canon lenses AF and I have an almost FF FOV with my lenses. I don't have eye AF with any of them but AF is quick and reliable. Face detection works. The menus on the A6500 are still not the most user friendly but I didn't get a headache dealing with the camera like I did when I rented an A99 for a weekend. Overall I'm happy with it, although I did get the 3rd party grip, not just for the extra battery (I WISH they did it like Fuji so you have 3 batteries in the camera), the grip just really helps making it more comfortable to hold.
I was very intrigued by the performance of the A7Riii but there was no way I was dealing with 42mp files. After seeing lots of Youtube videos of people showing that their Canon glass will not only AF, but will eye AF with the A7Riii, it means the A7iii will do just as well, and probably a little better. That helps, especially with the amount Sony charges for their native lenses! Ouch. I can see myself slowly transitioning my glass purchases over to Sony now.
I'll wait a few months, but I'm 99% sure I'll be purchasing an A7iii by the end of 2018, and most likely in the Oct time frame, before holiday photo sessions start kicking up! I own a couple of 6d's because they do what I need: good ISO, DOF control, the usual FF advantages...but it was an almost $2k camera when it came out and it only has one real AF point. I deal with it because I don't need/want the extra weight/features of the 5d series...but I never fooled myself about how the 6d was Nancy Kerrigan'd by Canon. I got them second hand so I'm looking at minimal loss when I sell. Not to mention, what I paid felt much more in line with what the camera was worth compared to MSRP
If Sony puts a swivel screen on the A6500 successor, or even an A5xxx, I'll be done with Canon bodies. No swivel screen and not implementing touch screen all the way are pretty much the only real deals now for me. Mostly just because they are pretty "easy" fixes that would make the A6xxx series seriously hard to beat for bloggers/Youtubers.
Wow, I just realized how much I rambled on! My apologies! LOL! In conclusion, YES I am excited about the A73 and will be getting one. It looks like it is going to be really hard to beat when it comes to what you get for your money