One thing I think makes it unlikely that we will return to the big bad federal government cracking down on weed is how the change has come. It has come from the bottom up. It's the people who voted in these states for reform. While the DEA surely still busts people for weed in some states with their behind-the-times laws (DEA agents like busts because it makes them look good to their bosses), this should soon be a thing of the past. For the federal government to go, "Nope, we're cracking down on all of this weed in Washington and Colorado" would be a direct, obvious, and blatant trampling of the voter's will. No political side, Republican, nor Democrat, wants that bad press.

Beyond that, it's just a matter of stating the logical arguments against prohibition. It seems like that's about the only way to overcome the hysteria common among those who are ignorant about drugs. The only thing is, truly legal psychedelic use may not be feasible, as the numbers of people just aren't there to be represented on a societal scale.

Are you asking about US or whole World ?

Anyway I would say with current world governments setup there is no hope. For example where I come from you get years in prison just for a little bit of cannabis. Definitely no hope here

In US only the government can legally (but secretly of course) import and sell drugs so no hope there neither Or you think they will give up one of the best businesses they have ?

SO I SAY NO HOPE UNLESS WHOLE WORLD CHANGES AND WILL HAVE REAL HUMAN'S INSTEAD OF PSYCHO'S IN OUR GOVERNMENTS AND HIGH POSITION'S.

It depends on where we're looking at. There is already a fairly low risk of punishment throughout much of the wealthier parts of Europe. Even suppliers are not in the same kind of jeopardy they were a few decades ago.
But I see things moving in the opposite direction for a majority of the world's population.

Indian police are starting to crack down on narcotics more than in the past. Most Muslim countries are also starting to increase the amount of policing they do on this front.
So maybe in America, that had some of the most constant and probing police activity, it will improve. But throughout the world? I'm not seeing this trend.

In ye olde land of oz the general populace seems to have an attitude more like america in the 50's than 2015, lots of fearful conservative voters and both major parties controlled by right or center right factions. we are doing silly things like moving towards a 2 tier health system to be more like the us, giving health insurers more control over what care you can get, all things that america is finally starting to address, our drug laws are inline with the united states federal drug laws and only now in 2015 are we finally seeing an assessment of medical marijuana take place, in one state (victoria). news article here

it does tire me out some knowing that we always lag several years behind the rest of the world it seems that australia loves the status quo a little to much

Yes, there is hope. It's happening. Have faith and pray.

Historically the US has been the main force pushing for the war on drugs internationally, forcing other countries to follow suit. If/when the US legalises weed many others will soon follow, until then I can't see it happen. Of course more totalitarian governments will still continue enforcing their drug laws, but many countries are simply waiting until the US stops breathing down their neck. When cannabis is legalized in the US and then Europe, shrooms will eventually follow for recreational purposes and peyote/ayahuasca/iboga for religious purposes (ea not produced commercially and sold in shops). LSD, Ketamine, MDMA etc. will likely remain limited to medicinal purposes and remain highly restricted in the for see able future.

Those are all just speculations of course.