Anecdotally in the Denver/Boulder area I haven't seen an impact. People who drink haven't converted to pot, because - IMHO - it's been "decriminalized" for so long. At places I work we still go out for a beer after work and restaurants are generally unwilling to allow pot products as they are alcohol (that may be a corporate or regulatory thing though).
The Guardian published an article stating that alcohol consumption (specifically tax revenue) has actually gone up: http://www.theguardian.com/politics/2015/aug/31/alcohol-indu...