It is not the same case.
Many people complained that the iPhone was too small. Nobody complained that the big iPad was too small. They complained that the iPad was too big and so Apple released the iPad mini.
Not exactly, I know. However, the regular iPhone 6 fulfilled that burning need for a bigger iPhone, and then the the 6 plus took it one step further into the "phablet" territory. I don't remember too many people preemptively demanding an iPhone phablet or anything more than what the 6 is, but collectively we scrambled to buy the 6 plus until it became scarce.
I do believe they'll do well to release an even larger iPad, especially if it it packs on a higher resolution for some real added screen real estate. That would make it much more viable as a professional device for design/document editing.
If it's 2048 x 1536, just blown up, that will be a shame.