"I was looking to buy that current TS 24mm, but as Canon announced to release new TS lenses soon so i just looked at one of the new TS lens, but i am looking to try to find many job in architecture and interior design photography in my country, and you know most of them are looking for large print for posters or billboard, so what i can do if i can't afford higher MF and LF bodies?"
I actually think there is no better way to learn AP than buying and learning to use a 4x5 VC. I agree with GB about that-it teaches discipline.
Having said that, as per DSLR and posters and billboards. I doubt most of your images will be used that large. Most in fact will probably be used on websites, magazine spreads, PowerPoint presentations or notebook size design proposals. A 21 MP camera is fine for all of that and more. But you could shoot a billboard with a 5MP camera and uprez it, many have. The viewing distance is so great on billboards that fine quality is lost. As per occasionally needing a large poster? Know your clients specific needs and learn to stitch with your DSLR.