Opening a vape store now could be very profitable and I see no reason not to. Just like adjusting for impending market forces on any business you need to plan a business strategy according to market potential over time taking in all considerations. For example: Do not spend a lot of money on the storefront setup anticipating a short term profitability rather than a long term investment. Do not sign a lease longer than 2 years until the dust settles with regulation. Plan on reducing inventory to negligible levels near the end of the lease term if regulatory hurdles are insurmountable before a new lease term is entered. You will be in a better position to negotiate good lease rates for the next lease term if regulatory issues are manageable, leaseholders will be quite flexible in renegotiating a lease for an existing tenant.
In SoCal there are so many available storefront rentals available it is not at all uncommon for 1 to 2 year lease terms for a new lease contract if the lessee has realistic expectations. Just be aware a leaseholder will not be willing to do buildouts or significant improvements for a short term lease (generally less than 5 years). The new business owner will need to incur costs such as new flooring, wall treatment, etc. 1 or 2 year leases will be more expensive month to month for shorter term leases, which is fine for both parties if the business is structured with this in mind. A business opening a second location with a positive history in their first location is very likely to get quick approval for a shorter term lease based on the history of the 1st location.
Opening a short term business with good planning is not really a gamble and with proper management can be very attractive. Look at all the 3 month leases for Halloween stores and Christmas stores (pop-up stores) that crop up year after year. So yeah, done right this can a very positive venture for the short term with the only gamble being will it also be a profitable long term investment. But done right, negligible downside.