The most pressing concerns with Slayer’s tour shuffling should obviously be with Tom Araya’s health and fans left in limbo while the Megadeth/Testament tour works out scheduling, but it also creates significant doubt for those who thought a North American “Big Four” of Thrash tour was not only possible in 2010, but imminent.

With the European “Big Four” events scheduled in mid-June, and “American Carnage” still in the way, a Summer option is unlikely (it remains unclear whether Araya’s recovery will affect European plans as well). We hear “American Carnage” is being rescheduled for an August/September timeframe, so Fall 2010 is out. After that, Slayer and Megadeth (the latter of whom is now doing two full US tours) would likely want some time off the road for rest and to avoid over-saturation. We’d also bet the cold months of early 2011 aren’t an option, as the cost of a Metallica, Megadeth, Slayer and Anthrax bill would force the tour into large-capacity venues like stadiums and outdoor amphitheaters, leaving Summer 2011 as the earliest we’d see a “Big Four” tour, if ever.