The problems listed here for a manned Mars mission seem to be of 3 types
1) Getting there safely
2) Once there, surviving long enough and well enough to do good Science (or why go?)
3) Returning.
Getting there safely depends on sub-issues such as the number one issue, the definition of "safely". It seems to me that with the possible exception of radiation protection, most issues are within a decade of resolution. NASA is already backing a number of propulsion systems that can vastly increase safety by simply reducing elapsed time. Electric, Fission and Fusion are in the works and while a practical fusion drive might be achievable within a decade, fission drives with good power to weight ratios have already been built and tested. A finished product has high odds for success given a decade and the money to develop it The biggest problem there is Public Opinion, not an inconsiderable obstacle, but at least possible. Reducing trip time to roughly 90 days makes huge difficulties either diminish substantially or just go away altogether.
Returning is a much greater issue since there exists no infrastructure on Mars for liftoff from Mars and the concept of sending a parallel mission to provide even the lesser amount of capability for Mars gravity adds great, possibly near insurmountable, complexity and cost. Possibly the best solution for this is not planning for return at all or within the foreseeable future. This isn't completely unreasonable since more than 200,000 people applied for Mars One and most of those understood they may not return. More than a few have asked themselves "What if it is certain I will not return?" and they still applied. For reference see
Still even if we say those two are essentially solved, the remaining problem is still extremely daunting. The difficulty of just supplying basic needs (medical, food, shelter and oxygen) are massive obstacles requiring a huge amount of cost and effort to overcome, even if we assume and accept it is basically a "suicide mission". There is little point in going if it is impossible to get a return on investment, beyond the personal one of "immortality in the history books". Additionally, that "immortality" would certainly include considerable negativity associated with a "suicide mission" without a substantial return... more than just historical. Who wants to be remembered as a murderer?
If we don't assume return, then nothing physical can be harvested so that leaves only information, scientific information to be gained. This requires Mars quality space suits, instrumentation, and the expertise to employ them (and good judgment) not to mention habitat. Although it seems the South Pole is likely to have the most readily available water ice, even the means to harvest that is unknown technology especially when one consider the weight of any digging and processing tools. However, a digging tool might be cost effective if it is also used to create safer habitat. I haven't seen many plans that involve underground habitat which seems would provide helpful radiation protection at no transit weight penalty, so possibly there are intrinsic problems there that I haven't considered.
Again even if we consider habitat, water and oxygen solved as above, it still leaves medical (both medicine and training beyond mere First Aid) and food. The average adult consumes 6 pounds of food per day. Multiply that by crew size, likely 3 or 4 (let's use 4) and we get 24 pounds of food per day. Even a piddling month stay means 720 pounds of food just for one month. This is not at all trivial even if we assume we have the means to provide decent nutrition without spoilage, and that is by no means a given.
So the bottom line it seems to me is - Yes It is within the realm of possibility to land 4 people on Mars within a decade but even to do just that and assuming they die within a day or two after "phoning home" with a few man/hours of actual Science as a payoff - just that involves huge commitment that I just don't see happening in that time frame. On one hand everything is easier after the first time but even if the crew are actually willing to die shortly after landing, who is willing to send them there for that little payoff on a guaranteed suicide mission?
My guesstimate is 30-40 years given the current level of commitment to advancing space exploration will make many of current difficulties a LOT better odds. I hate to say that since I probably won't be around to cheer and enjoy the data stream, but we are talking reality, right?
. Figure an unmanned resupply periodically. Could you stay forever? Probably not, but why would you need to? Oh, and use an ion-drive ship to get you there faster than the blast-and-coast method. 