This is already the case. I rarely have a need to take out my SLR - it's just too bulky to have a reason for it, unless I'm going on an adventure where photography is one of the or the main purpose.
I've gone on hiking trips where my "challenge" was to only use my phone camera. It wasn't much of a challenge for landscapes.
Most people are like that. But when I go for a 'photowalk' I cannot imagine not using my (#1) DSLR (or my (#2) super-duper zoom point-and-shoot camera).
Phone (imho) is for quick and dirty, not for a 'it's time to do proper photography'.
I've gone on hiking trips where my "challenge" was to only use my phone camera. It wasn't much of a challenge for landscapes.