you don’t even know how much yet, 64gb v 128gb base too.
64 VS 128 is not really a thing it's just a marketing move from Apple to make "Pro" more credible.
Just compare expected price of both model for a same capacity.
According to the leak, the 256 non-pro should be cheaper that the base 128 Pro model so if you don't value heavily the smalls adjustements of the Pro model I should just go for non-Pro.

But it depends of your needs !
Maybe the Pro will have more improvements than expected but this year, as or right now the "Pro" 6.1" seems closer than ever to non-pro model, so it's very logic the price gap is shrinking (OLED for the whole line up is a big thing).
Real question is do you value and would use (and not once a year) those "pro" features ?
And this is very personnal and depends on your needs.
The only thing to avoid is to buy a "Pro" phone for irrational reasons (I like the color, it's Pro so it's for me, I want to show off with 3 sensors look, etc.).
Just buy the appropiate device for yourself given what you would do with it ! Both will be insane device and IMO the Pro model is worth buying if you are thinking using telephoto (not once a year), it's good device for photo enthusiats and influencers but I think that it is a bit overkill for the mainstream audience.
I honestly thing there is no wrong choice between the two once you have truly try to guess what you would do with your new phone : true storage need, do you in real life use a lot telephoto etc etc.