What the price will be is anyone's guess, and you could be right, but I don't actually see it that way at all. There is nothing in the rumored specs that would suggest this should warrant a very high price. It's just got a higher resolution sensor. If anything, *on the whole it's going to be a lot less of a camera as compared to the 5D III an upcoming 5D IV: poorer ISO performance, less video functionality, etc. Look at Sony and Nikon; they haven't priced their 36MP products much higher. In 2012 did the $3000 36MP D800 seem like a "high-end" camera compared to the $3500 22MP 5D III just because it had a higher resolution?
Yes, Canon can absolutely give the 5DS a $4500 price sticker, it is entirely their perogative. But if they do, then I'm likely to go with Sony's 50MP camera, which will probably be priced far less. Since 2012 they have been losing customers to Nikon and Sony; customers seeking higher resolution options. So, it would be ironic if, after finally providing its customers with a high-resolution camera, they continued to lose them simply because they refused to set a competitive price.
One more note on value: if this 5DS has a Canon sensor, it's probably going to be underwhelming in the dynamic range department, compared to the Sony counterpart. That's even less of a value from a sensor performance standpoint.
Anyway, no one is "wrong" (yet), these are just some thoughts...they well may be proven wrong.
["Preparation H feels good on the (w)hole." - Dr. Evil]