Will dust storms be more frequent in the future?
Most dust storms occur down-wind from areas with a lack of moisture, little vegetation, and high soil content.  Vegetative roots help to keep the soil intact when there is a lack of moisture. So any shift in the future that leads to a net decrease in vegetation, net decrease in precipitation, or an increase in exposed soil content will increase dust storm occurrence.  Thus, the most plausible reasons for increased dust storms in the future that have related scientific research are: 


land-surface changes due to human influence: forests/vegetation being replaced by land management practices for agriculture or mining that do not sustain roots in the soil or expose more soil
decreases in precipitation (e.g. due to climate change) that potentially lead to desertification of the region.
diversion of rivers for human use, thereby removing water from any ecosystems that were previously downstream
extreme cataclysmic events (e.g. comet impact or nuclear war) that causes removal of most vegetation


So, in my opinion, it is a very real possibility that if humans continue to cause a net decrease in vegetation... there will be increases in dust storms.  However, there are good land management practices that can curtail dust entrainment into the atmosphere, such as those adopted after the historic 1930s "Dust Bowl" in America.

Finally, from IRO-bot's comment link to Wikipedia dust storms: 


  It has been argued that recently, poor management of the Earth's drylands, such as neglecting the fallow system, are increasing dust storms size and frequency from desert margins and changing both the local and global climate, and also impacting local economies.