Can you make an option to use old HUD when the new one comes out?

No, they can't. There's a chance that the changes they made to connect the new HUD to the game will break the old HUD, if not now then later on. It will cost Riot more time and money to keep the old HUD working, and could potentially hamper them later down the road (if, for example, they came out with a champion that needed some custom HUD work, similar to DJ Sona's radio button).

Why wouldn't you want the new one? It looks so beautiful and clean. However, streamers will have to change their setup.

No it isn't, it's amazing. I love it, anyway.

I like the "I do not like the new one" part

Yeah, the new one's bad.