Not really; with the NSA, FBI, and IRS hooks in general-communication, finance, and general social-mapping records they have a defacto registration. Yeah, they can say they aren't breaking the law by having a database for firearms, but they can generate all the requisite data from their giant data-centers.
And what is the purpose of registration? To find who has firearms. Attacking the capability to resist is the fundamental concept of war — and you say we're in a war, so how can you deny that the enemy would want to deny the means of resistance?
The other thing that our enemy wants is the ability to appear to be "the good guy", if there's violence he wants to be able to say "I'm the authority, so I must be the good-guy." This is why, I think, there's been so much pushing against general American values &mdsh; once someone lashes out they can claim to be the ones attacked.
Then they will complicate the process to the point it will be near impossible to comply without risking a federal felony.
They will do it is small baby steps A.K.A. the Overton Window approach...
In fact I think such an operation has been in effect for several years.