If only the United States were not currently dominated by politicians and lobbyists that treat politics like a game, then maybe we could adjust our drug policy to be effective. Portugal seems to have the right idea. Personally, I think a bit more extreme measures could be taken beyond decriminalization (make it all legal and tax the drugs like crazy). Nevertheless, a policy like Portugal's may be exactly what the U.S. needs, especially to determine how things would change with such a change in policy (in terms of numbers of drug users and drug related health issues).
As for paying for the treatment options for addicts, I doubt that there would be an issue. After all, with such a large portion of incarcerations being drug-related, the money saved on prosecution, prison and law enforcement could be transferred to paying for treatment. It could even be possible that we could CUT part of the budget. Then again, maybe not. Especially if we took the exact route Portugal took considering they still seem to track down drug users and have consultations with them very similar to court proceedings.
One thing is obvious, the current "war on drugs" policies are not working. They need to be changed. It seems Portugal has the right idea, so the U.S. should try taking a page from their book.