"What changes should be expected when purchasing products, and when would this all occur?"
The prices will almost certainly go up in the short term by about 20% due to taxes. However, the ability to have additional friends join you in the dispensaries (without having the get their cards) will probably increase their traffic, and initially the novelty will be exciting for a lot of newcomers I should think. My brother is a good example of a huge market of people who live in the 'burbs with kids and come into the city occasionally, and might want to hit up a dispensary for an evening with a hotel.I find it funny that a lot of folks would rather meet people at a dispensary rather than a bar which is full of douche-bags. Longer term, more cool new products will come out - (e.g. bubble baths, lip balm, more variety of candies and innovative dabs) - a lot of these are available, but will likely have broader distribution and hit newer markets in much larger volumes.
Then there will probably be price wars, new channels, etc.
It sounds as if cannabis for adult use won't be available for purchase in a legal store until 2019. The medical and recreational framework will need to be developed in a process called "reconciliation". The impact to the consumer will be profound. With standard operating procedures in place, consumers are surely going to see more professional products available on the market. Consistency is dosing will no longer be a marketing platform as it is now, but will be standard across the industry.