Of course I really think this is a real issue. The Federal Marriage Amendment has already been introduced in the House and the Senate Majority Leader has endorsed its introduction in the Senate. Do you think either 145 representatives or 34 senators will vote against the motions? [DOMA passed 85-15 and 342-67]
Once it clears the Senate, it will require only one member of each State legislative chamber to present for ratification. At that point, every legislator will have to go on record in some fashion or another either in support or opposition to gay marriage. I've counted at least 23-26 States that are likely to ratify in the very next session, with a minimal amount of political pressure.
The FMA advocates will need focus their funds & energy on but a dozen or so States to bring about ratification within the next seven years. If the fail to do so under the current composition of those legislatures, they will no doubt make it the central issue in the following election. Based on the Vermont precedent, the likelihood that this issue could turn over any recalcitrant legislatures is quite strong.
Meanwhile, there's an excellent chance either Massachusetts or New Jersey will legalize same-sex marriage and spark a nationwide 50-state court battle as well as throw FMA supporters into hyperdrive. That's aside from the liberal media furor & gay family sob stories & whatever. There will be a race between FMA and an eventual SCOTUS ruling (which would be irrelevant, anyhow).
The likelihood that the FMA will not come into force is exceedingly slim in my view unless the Dems decide they will stand or fall on this issue & halt its passage in the Senate. I'm not holding my breath. The only other possibility is if GWB [meaning Rove] intervenes with the House leadership to kill this proposal.
BTW, I think Washington, Oregon, New Mexico, and Minnesota will prove pivotal to the success or failure of the movement.