I'm not an expert on EMALS, but from what I can remember from Uni plus some comparisons with other aircraft suggest to me that it won't be a problem. Comparing the F35C to the lovely old Tomcat-the F35c has more or less the same max takeoff weight (about 70,000lb), bigger wing area (668 sq ft against about 550 sq ft) but much less draggy airframe, similar dry thrust (about 28,000 lb) but a little less with full burner (43,000lb against 57,000lb). F14 went offthe deck at max weight at about 155kts, with good broad spread wings. With those extra wing square feet and a good lifting body shape, I'd guess f35c takeoff speed at max weight to be similar to the F14 (though cant find any figures on that, so happy to be shot down!).
So EMALS plus ship speed has to reach 155kts to throw a heavy F35 into action.
The info I've seen on EMALS says it can throw a 100,000lb aircraft to 130kts, so an extra 25kts of ship speed would be enough to reach that 155kts even for a plane 30,000lb heavier.
Considering how unlikely it is we'd ever load an F35 to the gills like that, I'd imagine an F35 would leap off the deck!
Im not a navy man, though gents, just interested in the subject. So others may be able to shoot holes in my argument. Don't kill me!
Peter
http://www.edn.com/contents/images/207108.pdf