Of course it's possible, lots of things are possible - the question is not whether it's possible or not, but whether it's likely or not, given what we know.
MS apparently knew that the PS4 was in all likelihood going to be more powerful than their box (since they'd have a high % of their BOM going to Kinect) and would have developed their strategy accordingly.
So they're definitely not going to be running around flailing their hands because the PS4 will have games that run at 30% higher resolution or something.
I don't think BOM compared to PS4 was anything Microsoft were concerned with, as by everything that has been revealed about PS4 thus far indicates it is going to have a significantly higher BOM than Durango.
I think Microsoft started with a price point they wanted to hit. Then they had a feature list that they wanted to have. And finally a performance target. Throw all that together and we end up with Durango.
It could be that they didn't expect Sony to potentially go for another loss leading console design. Or they really don't care if Sony one ups them in performance. Looking at the state of PC games, while the performance delta with same features enabled between a 7770 and 7850 is fairly significant, you only have to look in our very own PC gaming forum to see users there that turn down graphical settings without themselves being able to perceive any noticeable visual differences without a side by side comparison.
I do expect things to shake out differently with next gen consoles however. Since most of the games that the 7770 and 7850 had to contend with were ports from consoles with very limited memory, assets generally weren't going to push things much.
Art and art assets may play a much more significant role for Durango and Orbis and hence, why I expect slightly lower resolution for Durango games, but that when viewed on a TV at most people's viewing distances, people won't be able to tell the difference without seeing them side by side. Especially when you factor in the likelihood that the game UI and especially text will likely always be 1080p.
And, of course, this is all assuming that the performance level of Durango's GPU is roughly that of a 7770 or slightly higher and nothing that MS have done on the hardware side has made it more performant than what one would expect from the rumored information available.
TL: DR - PS4 being more powerful than Durango has nothing to do with the BOM comparison between the two. In other words, Microsoft didn't really care what the BOM of PS4 was going to be as they were following their own business plan. Hence comparing the lower total BOM of Durango to the higher total BOM of Orbis doesn't factor in to the design decisions that MS undertook.
It does allow them the luxury of either pricing lower or having higher margins and profit levels, however.
From the tech side, I'm still interested to see how things turn out. I'm hoping, but not holding my breath, that after each console is finally released to consumers we'll get a more in depth look and explanation of each consoles hardware. I would find that very interesting.
Regards,
SB