minibus
airbus.com has comprehensive specs for these aircraft - look under aircraft families.
DXB-JFK = 11022km great circle
A345 range - 16700km with 313pax
A388 range - 14800km so in theory it could make it but would depend on routing due winds etc.
SIN-NYC for example (15348km great circle) is probably too tight unless underloading the 380.
In general, A380s will replace trunk routes served by 744s, 773s, 333s rather than thin routes served by 342s, 345s, 772ER etc. but airlines will probably try to use 380s on busy airports like JFK.