HTC was originally rather adamant about keeping the U12+ as the sole release within the family. There is still no word of a vanilla U12 model on the horizon, but the rumor mill has been going on about the "Imagine Life" - aka HTC U12 Life. In a new development, a fresh pair of schematics of the alleged device has surfaced online, Showing off a design quite reminiscent of the Google Pixel line. By the looks of things, the U12 Life might have a dual-tone back. Unfortunately, since this is a schematic, we can't really know if this entails two separate materials, like on the Google...
Source: https://www.gsmarena.com/the_htc_u12_life_might_feature_a_pixellike_twotone_design-news-32596.php