Unless your investments did brilliantly.
Retirement means you dont want to make mistakes, you have to get it right.
As you do a bit of everything the ultimate all rounder had got to be the 5DIII.
Its very good at sports, and portraits.
I appreciate having loads of Accurate AF points even in Portrait work. I also value the hyper sensitive AF points.
IQ is excellent. OK technically some say the 6D is marginally better, what by a wisker.
Retirement also may mean you will want your investment to last and be reliable.
I feel the build quality of the 5DIII may avoid costly repairs, may last longer.
More importantly it avoids the - oh I wish I had got x - but now cant really justify - selling y .
Get it right first time! Or at least dont have buyers "often unjustified remorse".
The other factor is one has to recognise Canon is a long way behind Sony in sensor technology, so far it makes me feel it may be 2 absolute minimum maybe 4 years befor they come back with something competitive. So this purchase will have to last you some time.
I suspect the 5 will sustain you better for a long period, may hold its value better???
But you will definitely be happier holding on to a 5 build quality for say 4 years, than a 6.
So my advice is get the 5 as you can afford it. But compromise by selling the 70D to help fund the differential.
My advice is a little flawed - on one count - as if you "up your game" and start getting paid work, you are rinning a risk not having a backup body.
Eg today had a 6 hour paid shoot , stopped for a break, recomensed only to find no AF, no AF illuminated points. Shutter would not work! OMG. OMG!!!!!
NB it was a 90 mile drive there, and 90 back ( nb UK petrol prices and a 5 litre car)
Plus the major embarrassment, of letting someone down.
Plus the model has a chance of becoming famous ( can not say how or why for confidentiality reasons ) so part of the deal was my right to sell the images as well.
So if this screwed up I could miss out on a lot! Potentially £000's. I very much doubt if she would have given me a 2nd chance!
Morally would I have to pay her for her time!
Trust me its a nightmare. What only 7 months old and 10,400 clicks on. With a Shutter rated at what 150,000!!! 

Total relief ! I was in Portrait mode and had forgotten to switch on the grip power!!!
But is scared me.
But I would still sell the 70d to fund the 5D3 purchase. Maybe Ill do some research and find the same sensor as a 7D and buy the cheapest 2nd hand one I can just as a backup.
Also thinking about the Sony AR7 and a converter.
Canon EOS 5DS R, Canon EF 70-200 F2.8 L Mk II IS USM, Canon EF 70-300 F4-5.6 L IS USM, EF 40mm F2.8 STM , RC6 Remote. Canon STE-3 Radio Flash Controller, Canon 600 EX RT x4 , YN 560 MkII x2 ; Bowens GM500PRO x4 , Bowens Remote Control. Bowens Pulsar TX, RX Radio Transmitter and Reciever Cards. Bowens Constant 530 Streamlights 600w x 4 Sold EOS 5D Mk III, 7D, EF 50mm F1.8, 430 EX Mk II, Bowens GM500Rs x4