No, all that gateway shit is in your head. My wife has been smoking for years on end now and she's never even inclined that she wanted to try anything else. The only other illeagle drug I've tried was acid and it wasn't because I was bored with Pot, it was because I had read up on it and decided to try it out.

Bottom line, it's quite possible to stick to weed only. It's whatever you wanna you.