When the flood gates open to direct US investment there should be a mad rush to secure property, development rights and whatever licenses/permits will be required. Over time, new construction will increase, renovations of existing properties will be done. Not a quick process for sure.
Where we will probably see the biggest immediate impact is the opening of service type establishments. McDonald's, KFC, rental car companies, a Hard Rock Cafe, that type of thing. Then will come the retail stores, automobile dealerships and the progressive march towards turning Cuba into a clone of anywhere USA. Due to Cuba's proximity to the US, I expect US companies will enjoy a significant export advantage over countries further away. Branching out into the Cuban market will be hard to resist for for the "profits above all else crowd".
There is currently a stark absence of international goods and services available in Cuba compared to the DR. Here in the DR, SD/Santiago seem to get all the mainstream Intl fast food places and product offerings due to the need for an expansive customer base to support such operations. In Cuba, there is nothing, so I think there will be a mad rush on the part of businesses to secure locations and future opportunities. The DR will continue to plod along as it has for years. The economic conditions here in the DR are what they are and what they have have always been.
Cuba is new territory with nothing but opportunity which may or may not work for any given business model. That country won't change overnight, but billboards announcing {insert company name here} coming to this location sometime, should pop up like weeds. It will be hard for companies to resist securing a position in the new Cuban market because they know, "he who pauses is lost", and if they don't act quickly, their competitors will. Delay results in lost opportunity, apparently a cardinal sin in a money grubbing market place even if it does destroy the historic allure of that market place in the process.
As happens here in the DR, not all new service sector businesses will survive the long term, but they will try because that's what companies do.