How much should a long distance touring bike weigh?
People tour on everything -- bso's , specialized touring bikes, mountain bikes, etc. 

Find something that works for you and is within your budget. Unless you have a decent amount of experience with touring, I wouldn't worry about something that does 3000 km tours without breaking a sweat. You need a lot of planning to do something like that, which will affect what you carry (e.g. are you camping, staying in hotels, etc.), and you need that information and experience to choose the right bike for you.

For reference, a standard touring bike (like the Trek 520) is 13 kg in disc form for a 57 cm. Note that the weight isn't that big of a deal; how it handles long rides carrying loads and how tough it is (e.g. are the wheels going to break in a little pot hole) is far more important.