the 1d3 values are by now in very grasual decline, you have very little to lose by keeping it for the time being.
perhaps a lot to gain, not least a known quantity.
7d2 will cost 20-30% more for early adopters.
7d2 will need a couple of fw revisions to get it working sweet.
7d2 might not tick all your boxes... folk think of it as an action orientated camera, I think of it as canons first serious video dslr (it was the first with manual exposure from launch, the first with a pal mode from launch, the first with a dedicated video switch) so the new 7d might be the first with a 3x imaging block. it might be friggin massive. it might bethe first with xlrs built in! it might take the a7s route of reduced mp count for cleaner 4k video scaling.
I don't know. neither do you.
but you do know your 1d3.
Nobody apart from camera anoraks are going to look at a beast like the 1d3 and think, ooh that isn't a 1dx. or a 7d2.
And camera anoraks aren't generally the best photographers. hung up on specs. technically focused. boring.
Care more about your images, and what no 7d2 or anybody else can bring to them... you!
Might you take better pics with a 7d2? possibly. but not yet. so keep the 1d3
the 7d2 has been inevitable for the last 5 years.