Just as Lexus midsize luxury has both FWD MacPherson strut ES [for the mass public, and mums & dads], and the RWD GS for enthusiasts, I think Lexus should also have a full size luxury car in two body styles:
(1) A FWD-based or RWD-based upright body style with a spacious interior like the old 4LS for the mass public, and mums & dads, with hi volume sales.
(2) Together with a sporty low center of gravity front mid-engined variation like the current 5LS as a halo model for enthusiasts, and niche volume sales.
In the same way, I think Lexus should have at least two engines:
(1) A bread and butter efficient 3.5 V6 TT like in the current 5LS targeted to the mass public and mums/dads with hi volume sales.
(2) A V8 TT as a halo model for enthusiasts like Rhambler with niche volume sales.
I also think that it may be important for Lexus to match the body style to the type of engine too.
Such that a tall upright sedan body style like the old 4LS would be matched to an efficient 3.5L V6 TT for hi volume sales.
While a low slung 5LS body style matched to a hi RPM performance engine with niche low volume sales.
Presently, Lexus confuses me somewhat with their No More Boring Cars formula.
We have a bread and butter hi volume ES, an efficient 3.5 V6 TT, but no bread and butter full size luxury upright sedan with a spacious interior and a deep trunk for volume sales?
The current 5LS may have mismatched a low volume sporty niche low slung body style, to a bread & butter 3.5 V6 TT which is supposed to sell in larger numbers; think of the 5LS as a low volume sporty niche body style - with an entry level 3.5L V6 TT - for now.
No more boring cars, yet 5LS only has a 3.5L V6 TT, and no V8 TT?
No more boring cars, yet the RWD-based 5GS and 4IS are to be axed?
However, we may simply be speculating too much.
Just as 5LS was delayed by 12 years in the US, 5GS and 4IS may have longer 8 year model cycles, with a 2020 release of 5GS and 2021 release of 4IS?
A V8 TT will come - given the time.
Such that the low volume sporty niche new low riding 5LS will get a truly matching sporty hi revving low volume V8 TT - in time.
Which only leaves missing a taller more upright & spacious full size luxury sedan version of 5LS to achieve greater sales volume, but its up to Lexus how they want to design the 5LS.
Like the S Class & AMG GT 4 Door Gran Coupe, Lexus may have to develop the 5LS is two (2) separate body styles too.
A conventional upright spacious sedan popular with the mass public, and a low slung 4 Door Gran Coupe for enthusiast niche low volume sales.
Another possibility is that the traditional tall upright spacious sedan is extinct!
In its place is a choice between a sporty dynamic low slung sedan like the current 5LS, or a full size luxury SUV tall wagen.
I hope they keep the conventional tall upright sedan.
In the same way, the Germans have 2 types of SUV's.
The traditional tall upright boxy spacious SUV, and the lower & swoopier SUV 4 Door Coupes like the GLC and GLE 4 Door Coupes...