After working with my addict for 15 years, 3 rehabs, jail, etc., I can say that it is best to assume that your bf will struggle with chemical dependency for the rest of his life. The only question is - will he ever get to the point where he wants to enter active recovery.
I have often thought about that "point of no return" - where someone has done so much harm to themselves that they no longer have the strength (or brain cells) to admit they are an addict and enter recovery. And, the further down the wrong road a person travels, the longer the road back is. Drugs do actual harm to the brain.
Even in active recovery, there is relapse.
The thing is, we humans can get used to almost anything. So, if by some magic a "normal" (not codependent) person would take your place in the relationship, you might imagine what that person would do differently.
You insightfully identify that you don't really want to end it. So, as they say in the recovery literature, maybe keep the focus where it belongs - on yourself.
Why is it OK with you that someone uses heroine in your home - an illegal substance that if you were raided by police would be linked to you also - translation - felony. And do you think the police don't know about the dark web?
And with all addictions, some progress slowly, some progress quickly, but ALL addictions lead to a crisis of some type. So can you accept that every day that goes by you are living on borrowed time?
Are you prepared for the crisis when it comes? Overdose, raid by the police, arrest of your bf, health crisis due to drug use, car accident?
As a recovering codependent, what I have come to realize about myself is that I get over-focused on other people's problems to avoid doing my own moral inventory and my own 12 step recovery. So maybe the question shouldn't be - will he be an addict for life. It might be - will I be a codependent for life?
I would say, in whatever way shape or form you can - start working your own recovery. I received some wonderful advice on this forum once that said - "Work your own recovery with as much dedication and commitment as you wish you addict would work theirs". I think that saved my life. If you don't like 12 step groups, get a therapist, coach or start your own group. Try everything until you find something that helps.
At 29 you still have a lot of life to live - BUT - time moves quickly. And you could wake up one day and be 39 and still struggling with this. What do you want from life and how are you going to get it?
Wishing you all the best,