I dont think there was a redesign this year. The screen was made bigger and the SOC renamed.There won't be a redesign next year. There was a redesign this year.
Similar to how the X, XS and 11 Pro all shared near identical designs, I think this approach will also been applied to the 12, 13 and next year's iPhone. The same can be said about the S0, S1/S2, S3 watches all being the same with the redesign coming in the S4. Apple has moved to roughly a 3 year period for designing their mobile devices.
That said I dont think they'll make the squared version. It looks terrible and uncomfortable IMO
Not surprising SS does nothing for resale/trade in...only the internals are useful to apple and anyone buying secondhand is looking to save money; the aluminum is 90% the same and far cheaper.
I get the aluminum just so I dont feel bad damaging it/wearing it everywhere/getting a new one. Although with the move to starlight its either dark blue or SS with 4 instead of 2 year upgrade cycles for me.