LGA1151 has some significant limitations (eg: PCIe and memory bandwidth), I am certain that Intel did not make this decision lightly. Z370 are quite different from Z270 and this will cause confusion for many.

Perhaps Intel is banking on the Z370 chipsets being the Intel equivalent of AMD's AM4 -- a chipset that sees support until the introduction of DDR5 memory. Nonetheless, the Z270 chipset being unceremoniously EOL'd is an unpleasant occurrence for many (including ODMs).

To answer your question -- it is most definitely not a drop-in replacement. While they may use the same socket, they are not interchangeable.