An oversimplification but -
if the masses didn't buy a V20 because of the second display, not including it in the V30 could cause them to reconsider.
if the masses wanted "a phone that looks nice, good enough to compare to Samsung in aesthetics", going sealed/glass on the V30 could cause them to reconsider.
Relative to the market though, what's a high-end feature? Removable battery? Second display? I'll give you second-display - that is a differentiator.
But let's take a look at LG's homepage for the V20. What are the tent-pole features of the V20?
LG V20™: Superior Video, Photography, & Next-Level Audio | LG USA
Page title: "LG V20 Superior Video, Photography, and Next-Level Audio"
- Steady Record 2.0: Clearly Capture Life in Motion
- Hi-Fi Video Recording: True-to-Live Sound
- HD Audio Recorder: Studio-Quality Sound
- Hi-Fi Quad DAC: Let Every Detail Move You
- Front Wide Angle Lens: Fit More into the Frame
- Rear Wide Angle Lens: Get More In, Leave Nothing Out
- Dual Rear Cameras: Tell a Bigger Story
- Android 7.0 Nougat: You're in for A Real Treat
- 5.7" Quad HD Display: Innovation On Display
- Second Screen: Stay On Top of It
Besides the second screen, what is the V30 losing in terms of high-end features?