I can only speak for myself, but I am uncomfortable by your question because it's a question that isn't well thought through on an issue that you should definitely think through as much as possible. I would, almost without exception, say that in my law school the bottom of the class rank is padded with the "Law school seems like a good idea" type of people, where as essentially everyone that is succeeding are the ones that came into it with passion and drive. So yes, if you do not have that passion and drive, I would urge you to also consider alternative paths.
On a separate note, your final comment doesn't make sense. You asked a question, we are answering it. If that is your way of "being helpful" that is of course very "Socratic", but does not really make sense otherwise.
Yes you can certainly have more than one passion, I had a different career before going to law school myself. I have no problems understanding that.
But since you bring up med school and dentistry at the same time as law school, those "passions" are pretty much separated by Grand Canyon. All I said was that I would recommend you find out what you want to do with your life before you make this decision. By keeping every professional school as an option, I am inclined to think that you are motivated by money/prestige/both. Neither of those are a good reason for picking either career, in my opinion.
I honestly do not feel that a surplus of lawyers is where the problem is at (that is not saying it isn't an issue). I feel that the problem is currently the cost of attending law school, which forces law graduates to all target the high paying jobs. There are a number of "inferior" legal areas that are not overstaffed, but they are generally paying too poorly for a debt-laden graduate to consider if they have other options available.
My point wasn't really whether or not there were too many lawyers in the world. My point was that you should do what you think you would enjoy doing for the greater part of your life. Succeeding in law school is just as simple as succeeding anywhere else; work harder than the other guy. If there are too many lawyers in the world, that's ok as long as you make sure not to be one of them.