Well by "consensus" you mean sheer guess because no one except the inner circle at Infinity Loop would have any privy to that kind of information. If you are hanging your hat on "analysts" their closets are stuffed to the rafters with bad guesses. Who is included in your "general consensus"?
What solid info do you have that the 16GB is going to be "phased out?" The fact it's in short supply, as others have pointed out, can mean a number of things having zero to do with Apple canceling it.
Now maybe people are thinking back to the early killing of the 4GB iPhone. But that was a different story. 4GBs was never adequate for the iPhone, and that was way before the concept of the App Store. OTOH 16GB is quite comfortable for most, and frankly I can't even imagine why someone would need or want 128GB on an iPad, though I'm sure Apple will make one some day if the can get enough sizable NAND chips on the cheap.