I think you are talking about two different things here. "Happiness", whatever that means, I think is very different from feeling present and connected. Theoretically, I think it's possible to create a pill that makes one more connected. In fact, I think it's practically possible and would be likely to happen too, if there were money and time spent on the problem (which is where I get pessimistic about this).
Will there ever be a "happy" pill? No. Happiness is a result of values, goals, accomplishments, and things going well in your life, among other factors. No pill can create those conditions. After all, even with the drugs that are available (alcohol, street drugs), the response you get from them is dependent on conditions prior to taking them. And SSRIs, for that matter, are almost certainly placebos.