So far as I know, nobody is talking about this just yet. And that makes sense, given the need first to agree about what the broader contours of a congressional authorization---substantive coverage, modification or chucking of the 2001 and 2002 statutes, accountability mechanisms, and so on---should look like.
Still, if precedent is any guide, the words preceding an ISIS AUMF’s operative language could prove consequential. They often reveal Congress’s own thinking about the president’s standalone powers, for one thing; the preambles to the 2001 and 2002 AUMFs recognized independent presidential authority “to take action to deter and prevent acts of international terrorism against the United States.” (One draft 2013 AUMF, regarding Syria, seemed to sweep more broadly, declaring that the president has “authority under the Constitution to use force in order to defend the national security interests of the United States.”) For another, a preamble can suggest clues as to just how broad or narrow an AUMF’s scope really is---and that ought to matter, say, to a legislator keen to avoid mission creep between the enactment and sunset of an ISIS AUMF.
Don’t get me wrong: the operative clauses in any force authorization probably are of the greatest importance. But the words preceding those nevertheless will be important, too---and thus ought to be the subject of close legislative attention.