From an engineering development standpoint, the 4Runner will be built to minimize production costs, thereby maximizing profit margin (Toyota is in business to make money after all) while not sacrificing the QDR (Quality, Durability, Reliability) of the product (since this is predominantly the benchmark that drives their exceptionally high resale value and the main reason people buy a BOF SUV anymore).
After having watched several interview with sweers (the lead of the new Tacoma, who before that was the lead of the new Tundra redesign) it's pretty apparent Toyota knows the audience they're trying to target with their entire Truck line in North America. While I don't know who the chief engineer is for the 4Runner I would guess he/she and the Land cruiser Chief Engineer would talk routinely (similiar to the way Sweers did with the hiliux platform chief engineer and used his previous Tundra experience during development of the "all new 2016 Tacoma". It's the nature of business nowadays. incorporating lessons learned from all over the company and product lines...)
At the end of the day, all technologies for the 4Runner (and just abour every other truck/suv platform from toyota lexus) trickle down from the Land Cruiser, it is the design standard for Toyota BOF SUV's which is why it's considered the flagship. This platform goes through all the rigorous product development so when other models use it, they don't have to absorb the R&D costs...(Which is also why the LC is so freaking expepensive to absorb this new technology R&D costs for the first ... Toyota cannot afford to mess up the LC/LX platform in the world market) for example, kdss, crawl control all started on the Land Cruiser in 2008 with the LC200 and it eventually trickled down to the 4Runner for the 5th Gen release in 2010 on the trail model (Tacoma and GX just got crawl control this year on certain models... and none of these models cost as much as the LC200 with the same exact technology offered.... I digress) Overall, I would expect a completely redesigned exterior and interior to completely change the customer interface with the vehicle to try to reach the Target audience toyota is trying to reach (Whatever that is based on their surverys and feedback received). It has to feel new even if the guts are service proven otherwise no one would buy it.
One thing I know for sure, nothing of subtance will be debuted for the first time ever on the 6th Gen 4Runner. Look to other similiar platforms and trickle down from the Land Cruiser (e.g. the 4runner will likely get the old Land Cruiser 6 speed since it got an 8 speed for 2016 and while this may seem new to the 4runner, the LC200 has been using it for years... (Decisions like this allow Toyota to maintain the industry lead in QDR while minimizing new product development costs. It's how all good engineering companies work, not just automotive manufacturers.)
I wouldn't be shocked for the 4runner to have the same engine as the Tacoma with a different ECU tuning to achieve more low end torque. I also wouldn't be surpised for the 6th Gen 4Runner to get a mid year refresh with (lighter weight materials which will undoubtedly be used for the LC300 and introduce the 8speed tranny which is already offered for 2016 on the LC/LX platform ). These supply/ logistics chains will already be established for the Land Cruiser so for Toyota Japan to tap into them would be most cost effective... and probably lower their cost due to volume buying/purchasing agreements.
I do look forward to seeing what they piece together for the 6th Gen... they have a lot of service proven technology to improve the model for the North American Market. Overall I'd love to see the next gen 4Runner to have the same towing capacity as the GX model line but I doubt this will be possible without the 4.6L powerplant being offered as an option.... and I'm not sure they willing to do that. For me, this is the biggest issue for the next gen 4Runner, towing capacity (surprisingly the all new Tacoma has a 6400 towing capacity with the 3.5L V6. It would be nice if the 5th gen 4runner could match this spec...)