In theory, as long as backlogs exist in either EB2or EB3, there should be no leftover visas in EB3 because it is easy to interfile from EB2 to EB3. Any efforts to illegally spill over leftover EB3 visas to EB1 should be resisted and challenged by all stakeholders. Leftover EB3 visas in the current situation is nothing but a result of mismanagement by the USCIS and the CO combined. If this illegal funneling is allowed to get entrenched it will create havoc for years to come. It has already happened for a couple of years (at least in effect). Illegally moving these visas over to EB1 will never help backlogged folks as we now know that EB1 has a bottomless appetite for visas and will rarely if ever generate spill overs. Moreover, this kind of illegal spillover would only compound the injustice to people stuck in the line for decades where EB1 are barely waiting an year or two. Also, there is hardly anything to suggest that EB1 as a whole are in any way more meritorious or deserving than other EB categories. Lets all play by the rules, howsoever nonsensical they may be.