Thats what im reading too. But what has me leaning towards the Canon is of course the "Canon" name.. Sometimes 3rd party lens scare me for the future. You know Canon is stingy with their technology. so im not sure if a 3rd party lens will become obsolete 2 camera bodies from now. ...
I am not sure I understand your point here.
To my thinking, if a future 5dmk5 that comes out in 2017 is incompatable with a 2013 sigma lens, then it will be incompatable with a 2013 canon lens. No matter which lens you bought in 2013, it would need some updating. It comes down to how easy and expensive it is to update the 2013 lens. I kinda like the idea of the Sigma USB dock and anticipate that other lens manufacturers will be coming out with their docks soon.
Do you think it is possible that a 2013 Canon lens would work in a "2017 5dmk5" camera but a 2013 Sigma lens wouldn't? I can't imagine that happening. I could be wrong.
There are many reasons to choose Canon lenses over Sigma lens, but future compatabity issues shouldn't be one of them. Not with the lenses being constructed these days.
But what has me leaning towards the Canon is of course the "Canon" name
Just my opinion, but buying a lens simply because it has the name Canon on it is as unwise as buying a lens simply because it has the name Sigma on it. No lens company makes the "best" lens across their entire line. Especially when "best" depends on the individual photographer and their requiements.
Especially these days, it is important to evaluate each lens separately and base your purchasing decision on how this specific lens performs. There are people who are interested in re-selling their lenses. I never do this so my opinons don't incorporate re-sale.
I buy Canon lenses when the Canon lens meets my requrementes. I buy Sigma lenses when they meet my requirements. I try to keep an open mind about the lenses being made today. These third-party lenses sometimes (not all the time) are better (how ever the individual photographer interprets it) than the camera manufacturer's lenses. Sometimes the camera brand is better. And even sometimes they are the same.
One thing I have found out is that buying a lens these days is a lot more complicated than back in the film days. LoL Sometimes I feel we have too many good choices.