Maybe, or the inverse could happen. Not much. People have been carrying guns illegally in national parks for decades. The law is talking about trained, CHL holders only being allowed, and the stats show them to be ultra-law abiding, with very few incidents. Time will tell. (unlicensed people will still illegally carry, no doubt)

http://www.txdps.state.tx.us/administration/crime_records/chl/ConvictionRatesReport2006.pdf