Crime will go up because Demand will not shrink to the same degree that legal Supply will and, by definition, making something illegal increases the amount of crime.
People will still go to Denmark for the same reasons they now do, less of them will, sure, but because it would still be a LOT easier to obtain pot illegally in Denmark than it would be in the UK (for example) you won't be rid of drug tourism at all. There would be a shit-ton of money to be made, now, on the Netherlands drug black market because the policy pretty much creates an entirely new market for them to exploit - People who can't get onto coffee house member lists and foreigners.
So there will be a rise in the amount of people illegally dealing Pot when there would of been no point before and, because this illegal pot is not controlled, it will inevitably suffer from the same problems that other illegally dealt drugs suffer from - Tampering and extortionate prices. And not just individuals, the odd coffee house here and there will be more "Relaxed" about their policies because of this brand new, cash filled, market. Just like Speakeasies during prohibition.
Petty crime may decrease, but at the expense of more serious crimes. Hell it's just as likely that whatever decrease in petty crime you see from drug tourists will be replaced by petty crime by drug dealers and their activities.
to summarize..
- All the money you'd make from foreigners buying weed will now go to the blackmarket
- All the money you'd make from incidental tourism from foreigners will go to another country (Sorry Denmark but your more liberal views on drugs and sex were your countries Unique Selling Point; Like London/Buckingham palace for England. Sure there IS more to see, but nobody gives a fuck about it)
- It creates a need for a black market, one which you will have no control over, nor benefit from.
- Crime will reduce in some areas but increase in others, most likely worse areas.
- Peoples habits wont change, the only thing that will change is that now they can be arrested for it.
I think Drug trafficking as an outgoing product will decrease, but not as much as I think illegal drug distribution internally will increase.