A Grand Highlander, a stretched Highlander with more room in the 3rd-row, makes a lot of sense to me. Toyota would finally have a true, 3-row crossover to go against the Subaru Ascent, Honda Pilot, Ford Explorer, Hyundai Palisade and Kia Telluride. (I never believed that Toyota would expect 3-row crossover buyers to buy the new Sienna minivan, despite its more aggressive styling.)
When this generation of the Highlander was introduced, I was surprised that it was neither a replacement for the 1st-generation, 2-row Venza (I believe that the 2nd-generation Venza is too small to be a direct replacement for the 1st-generation Venza), nor was it a true competitor against crossovers with larger 3rd rows, like the Subaru Ascent, Honda Pilot and Ford Explorer.
The Grand Highlander could also serve as the base for the expected 3-row Lexus TX.
I actually got curious last weekend and test drove a Highlander Hybrid Limited... potentially to replace my 4Runner. The +20MPG difference and new tech were really appealing.
Pretty quickly, I realized that the Highlander was not for me. I forget that crossovers are literally the in-between when comparing true SUVs and passenger cars... with a driving position that's between the two and driving dynamics that are neither as quick as a sedan or as substantial feeling as a true SUV. Overall, it's really nice though, and perfect for someone looking for extra space, new features and great MPG. It was incredibly solid and planted on the road, and I liked how it handled. The difference in TNGA products compared to their predecessors is immediately noticeable, and the Highlander was really impressive... but just not for me.
With that said, our Camry XSE V6 came in yesterday and we're picking it up (and trading in the IS) on Saturday. Driving the HH made me excited to drive GA-K in a sportier execution with more power. More to come.