Almost every single space enthusiast is excited about a Mars mission and when we are sending our scientists there. But from the communications point of view, are we ready to test the recent advancement to the technology? If not, are we looking for an alternate solution (lasers)?
The current DSN could be enough, depending on what the crewed mission requirements are. If you just want to communicate with voice and moderate-rate engineering and science data, then sure. If your requirements are to send back many channels of continuous 8K ultra-high definition video, then no. You would at least need to upgrade the DSN receivers to handle those kinds of data rates. With a big enough antenna and power amplifier on Mars, you could, in principle, transmit those data rates at current DSN radio wavelengths.
However, it would be much more efficient to use laser communication to meet those sorts of requirements, in terms of power and aperture. It is quite feasible to do so. There is no insurmountable problem with pointing, as speculated in another answer here. We lack only the money and the mission impetus to build such systems. Space and ground systems for Mars-Earth laser communications have been designed and proposed for decades, and a technology development effort is currently underway to prepare for the mission that might someday demand it.
Considering the other rather large expenses of crewed missions to Mars, it seems extremely likely that the small investment would be made in laser communications to support those missions and to provide better entertainment value from the mission back here on Earth.
Back in 2014, NASA issued a Request for Information concerning the use of commercial solutions for Mars relays. One of the key limitations outlined in this RFI was the very limited bandwidth of the current relay infrastructure.
In addition, the DSN is used for many other interplanetary missions (if not all, I don't have the data on this). Therefore, there is an inherent scheduling issue if one wants to maintain permanent communication with a crew on Martian soil, or in transit.
As pointed out by Mark Adler, the main barrier to laser communication from Earth to Mars may be the lack of money and mission requirement to continue developing this. Briefly looking this up, it seems ESA has reached a Technology Readiness Level of 6 for their LEO to Earth systems. NASA was at least planning to reach a TRL of 6 for their deep space laser communications by Mars 2017.
Concerning the pointing situation, a GEO spacecraft, which is only about 36,000 km above Earth, would shift its radio-frequency coverage projection by 700 km if its pointing is off by 1 degree. Lasers have a much more narrow beam than a typical reflector (or antenna). So the pointing constraint is even more stringent. I suspect that the solution we'll end up choosing in a few years is "plain-old" radio communication but at a higher frequency: the higher the frequency, the more power is needed to generate that signal, but the bandwidth is also increased. In any case, a Mars mission would surely have several redundant communication systems.