At 30 years old, your brother is old enough to figure out how to live on his own. I don't believe asking him to pay his rent or leave is the same as "putting him on the streets". I had to ask both my kids to leave - at age 17 and 18. They were young, naive, not working and very immature from their drug use.
But in each case, the pain of their chaotic behavior was worse than the pain of letting them learn their own lessons of how to live on their own.
As a mom, something that struck me was when someone told me -
My job as a mom used to be to keep my kids SAFE. That changes over time. We go from keeping them safe to helping them to PREPARE FOR ADULTHOOD. Our real job as parents is to help them grow into repsonsible adults.
At some point, that means NOT doing for them things they can and should be doing for themselves. It is hard to get up and go to work every day. It is especially difficult for someone addicted to a substance.
But until he faces the consequences of his choice to continue to use, he will not be willing to quit.
After all - if he has a roof over his head, a warm bed, a hot meal AND his drug of choice - why would he EVER quit?
Mom may not be ready to do this... she may need to lose her home to figure out that she can no longer protect her son. But she is very much like the addict... it takes the pain of continuing to do what she is doing before she is ready to change behavior.
Alanon helped me understand this. Alanon put me in contact with others who made the same choices as me, and who could tell me what it was like, and how they got to the point of being able to make those changes.
If you can, you might see if mom will go with you to about 6 Alanon or Naranon meetings. They can be very eye-opening.
I wish you the best.