These 24/7 services are all well and good, but once again are still useless for most people unless you happen to live and work (or drink!) on one of the three routes!
I would find the N21 very useful on a Sunday night as I could get the bus down to Pity Me and then get a lift the rest of the way when my mother finishes work at 2:30am. But, since there's no N49 I'd either have to walk the 2 miles into Gateshead, or get a lift to Gateshead, at which point I may as well just get a lift all the way there.
Even if they just did a 2 hourly service on some of the other key routes during the night, it would probably make the services a lot more useful for people!
RE: The return of Night Buses