pass into (something)
To shift gradually into some state or condition. The band was something of a one-hit wonder for a while, but now even their most popular song has passed into obscurity. Once the most grand and imposing manor in the entire region, it has passed into disrepair over the last two decades.
pass into something
to move into something; to fade away into something. Thoughts about the accident, little by little, passed into oblivion. All her old school chums passed into oblivion.