I currently own a BRZ. I bought it as a 'just in case' car, in case the new Z never appeared. I shopped long and hard for a new 370Z, my first choice. But the combination of my picky and specific requirements (red, Sport Tech, 6 speed) and most Nissan dealers I dealt with were complete sleaze, ended up in my not finding the car I wanted. We've had good experiences with a Crosstrek and WRX, so I bought a BRZ as a second choice. While it superficially seems comparable to a Z, it's a very different car, similar size but lighter, and of course much less power. It's undeniably fun to drive, but I like the 'old school' torquey V6 of the 370Z.
There is a LOT of rumor-mongering and speculation on the BRZ/86 forum about what the engine will be in the new GR86. Obviously, everyone is hoping for a turbo 260-ish hp engine, as that would address the biggest shortcoming of the current car - not enough power (though truth be told, it's enough to be fun in street driving). I personally doubt it will be turbocharged, and suspect it will be a naturally aspirated 2.4 with 217(ish) hp.
Toyota calls the shots in the car's development. While technically it's a 'collaboration', Toyota is about 10 times bigger than Subaru (in terms of revenues and market capitalization). I don't know the relative financial contribution of each company, but Toyota is clearly the 'senior partner'. I don't think they will do anything that would risk jeopardizing Supra sales. Especially now that the Supra is offered with a 4 cylinder 255 hp engine (though only with an automatic), a 260 hp GR86 with superior performance (and a likely $10k cheaper price) would cannibalize Supra sales. The sports car market just isn't big enough for both cars (maybe not even one of them). Even though Toyota buys the Supra from BMW, it's still their legendary brandname, Supra, the stuff of legends (and Fast and Furious movies). I doubt they would undercut Supra sales with the GR86.
The N/A 2.4 engine with 217 hp would have a modest torque bump from the current engine, but still wouldn't be anywhere near the same league as a Z engine. But, if Toyota/Subaru ever did see their way clear to allowing a 2.4 turbo engine in the car, then it would indeed be potentially tasty competition for the Z.
But when you dance with an 800 lb gorilla, you dance to the tune the gorilla calls, and you're finished dancing when the gorilla says you are. Toyota will decide what happens.
A bit of a dated thread, and this is a Nissan Z forum, but, what the hell, the BRZ is a competitor for the Z so discussion and comments are relevant and interesting (at least to me they are, but maybe I'm the only one who'll be cross-shopping the 400Z with the new BRZ).
I personally like the looks of the current first-generation BRZ better than the new one. To my old-school (and old man...) eyes, the styling of the new car is a bit of an incoherent mix of curves with Chris Bangle-like creases with the biggest rocket bunny side sills I've ever seen on a production car. It's disharmonious. The first-gen car was all curves and flowed better.
The interior looks like it's been "improved" in the sense that it's now more cohesive, with perhaps better quality switchgear. The instrument panel is now all-digital (which is in vogue), which is in some ways an improvement over the current car's mixed analog + digital dash (though again being an old-school curmudgeon I personally would have preferred an all-analog dash).
The biggest improvement is of course with the engine. Naturally everyone in the BRZ/86 community was hoping for a turbo engine, and of course that wasn't going to happen (because Toyota wasn't going to allow the car to undercut Supra sales by being more powerful and faster for a lower price). Truth be told, a 228 hp naturally aspirated engine is probably just about right for the car. Much more important than the raw 'hp' is the boost in torque, which now peaks at 3700 vs 6500 rpm, which should make the car much more pleasant to drive in the real world on the street.
The BRZ was never about straight-line acceleration. I always saw it as a modern-day version of a classic 1960's/1970's sports car, a MGB-GT, Fiat 124, Karmann-Ghia, or Opel GT for today. Since I grew up driving the sports cars of the 60's/70's (and once owned all of those), the power:weight ratio of the BRZ was fine, vastly better than anything the cars back then could ever dream of. 'More power' is almost always better, but I would always prefer a naturally aspirated engine over a turbo.
My daily driver is a WRX, with a 2.0 268 hp turbo. It's a great car and a lot of fun (though the ride is stiff, and makes about 3 hours the max my aging bones can handle). But to me, most turbo engines feel more alike than different. The driving experience for most turbos is, nothing down low because of low compression until the turbo kicks in, then WHAM-BAM!!! a catapult slingshot launch around 2500 rpm, and then it's all over by 5000 rpm. To my ears (used to a long line of N/A motors), it's also hard to get a turbo to just sound right. They can sound OK, but regardless of the performance, they often still have that choking sound if an asthmatic Italian grandmother struggling up a flight of stairs. The exhaust can be tuned all you want (and heaven forbid the blasphemy of electronically-enhanced sound), but it's hard to argue with the purity and visceral thrill of a sound like the Honda S2000. As much as the future of car engines is turbocharging, I personally would have preferred the old N/A 332 hp 3.7 in the new Z over the more 'modern' 3.0 400 hp turbo.
It will be fun to test driving both the new Z and BRZ, preferably back-to-back, on multiple long test drives. It's something to (hopefully!) look forward to on the other side of this surrealistic pandemic.