[tdj]

Not sure how many do this, but you're basically describing my situation, 8 min commute to Mitte, and relatively cheap. Due to the rent control, rents only jump after tenants change. An identical flat to mine, below me, was just now online available for rent for about 20% more than my rent is - and got rented out within a month, so there's demand.

I don't think there's a fear for displacement yet, there's quite a few plots to build up, or abandoned places that are torn down (e.g. Stattbad), and a bunch of new modern apt buildings coming up. But for now, it looks like Neukölln is the more desirable next-hip-thing.