Will there become two distinct definitions of marriage in America?

I think in 20 years (another generation), no one will care.

I believe this is a generational issue that we are on the cusp of.

Eventually it will just be about the venue, or where people got married. I got married in a Lutheran Church. Neither me nor my wife are Lutheran, however her grandmother is, so that's where we got married, and our marriage license says "religious ceremony" on it. We could have just as easily done a civil ceremony. I have a feeling family, friends, and the free market will sort this out.

Marriage is a legal contract, a wedding is a ceremony, either religious poo us or civil. The legal definition of marriage won't change, but the concept of marriage will definitely change. People confuse the two..I see that as being stumbling block for the eventual acceptance of this new reality.

Hopefully it will end with the state out of the marriage business. Except enforcing contracts between consenting adults, regardless of the parties to the contract.

The powers, rights and privileges of marriage will not change.
It is who can enjoy these powers, rights and privileges that has changed.
Just another step toward the complete fulfillment of the "all persons" concept held in the Constitution.

Please no more, stop the madness!!! Ahhhhh!!!! Marriage is marriage no matter who you marry. One definition.

Marriage no, wedding yes

Well in a way you already have 2 distinct definitions of marriage. You have a civil ceremony and a religious ceremony.
Allowing gays to marry, while offensive to many people for their own reasons, should never have had to been fought so hard. A civil ceremony is nothing more than going to your local government center, filling out the application, paying the fee and scheduling with a justice / judge to preside over the proceeding. There should be no problem obtaining a civil marriage license as long as you meet the requirements of age and possibly blood tests or whatever else is required. And no your gender should have no factor in it.
Religious ceremonies can get complex because to be married under that faith you normally have to meet the requirements of that religion, such as marriage counseling or something else. Religious marriages are harder for homosexuals because I would venture to say that 99% of the churches and religious leaders, generalizing here, are opposed to performing a gay marriage ceremony because of their religious beliefs.