Federal law takes a lot to budge. In fact, this law that's been around for ~50 years has remained unchallenged for the majority of that time. While there is some new uproar and hope from hippies everywhere that the law will change, Federal Law will remain unmoved for many more years to come.
I believe that the DEA will eventually change its stance on marijuana. Currently, marijuana is ruled as a Schedule 1 substance, meaning that it classified as having no medicinal properties. However, several states have issued legislation allowing legal medicinal marijuana. I believe that over time, with the increasing effort among individual states to legalize medicinal marijuana and the emergence of new studies and research about marijuana's medicinal properties, the DEA will begin to change their stance on marijuana.
For the most part, people that find themselves locked up in jail cells are often first-time non-violent users of marijuana. They take up a ton of space in jail, taxpayers money, all because they use a recreational drug that does not have nearly of a devastating affect such as cigarettes which are legal in America. I do believe it will take a while, but eventually, we will see a shift in tides, like few states that have decided to legalize marijuana.
No, marijuana will not remain illegal under federal law as the government starts to see more of a benefit to the use of this drug for medical purposes. The drug has a positive use that can help sick and dying people. The government is becoming aware of this fact so the law will change.