I think
@ssun30 can answer your V6 I6 question. Remember even S Class uses I6 nowadays.
It would be incredibly odd for a conservative company like ToMoCo to switch gears after 3 years of TNGA-related announcements and begin development of an I6 when they just launched a brand new Dynamic Force V6. Most Toyota engines live on a 10+ year cycle. V35A-FTS was deemed a flagship engine for the LS, so now we are saying that should have been an I6...? The existence of a brand new TT V6 and new co-developed I6 is making very little sense to me.
For Mazda, who hasn't had their own 6cylinder engine in decades, I understand starting from scratch and going with an I6 for boosted applications. For Toyota I do not see what they stand to gain or what sense it makes.
Lifestyle brand is best what a company could achieve. It ties customers to its ecosystem very much like Apple's success.
It is possibly a discussion for another thread, but Lexus' decision to attempt to become a "lifestyle brand" is one of their biggest and most damaging mistakes over the last decade, IMO. Lexus is not a lifestyle brand. There is no lifestyle to owning a Lexus when you can own everything from UX to LC. Young, old, black, white, European, American, fat, skinny, outdoorsy, indoorsy, high tech, low tech... there is no inherent value added by Lexus that you cannot get from another brand.
Apple - we use our phones for everything we do in our lives. LuLuLemon - launched and popularized "athleisure" clothing that people wear for everything from working out to casual work days. Work/shop/live urban developments - where our entire lives take place. Those are examples of lifestyle brands.
As you yourself note, Lexus is a (nice) way to get from point A to point B - while you are living your life/lifestyle. That does not make Lexus a lifestyle brand. "Experience Amazing" and lifestyle marketing has been a clever blanket diversion for Lexus to produce sub-par cars with marketing that makes them look like more than they are. Showing people eating food under tents and smiling wearing nice clothes does not make a lifestyle brand.
In the world of marketing, "lifestyle brand" is something of the past. As I mentioned before, it was a term launched 5-6 years ago when social media influencing became a new channel for companies. Many brands rushed to claim they too were "lifestyle" only to realize that many consumers see 90% of experiences and goods as a means to an end - not something they identify as part of who and what they are, aka "lifestyle."
Lexus would do well to get back to product messages. After all, that is what everybody wants: great products. Only problem is that Lexus has comparably few of them, so I am sure fluffy "lifestyle marketing" will be here to stay until we are further into the TNGA rollout with real tangible competitive advantages worth promoting.