>98% of humans born in first-world countries reach adulthood and have the chance to reproduce. This number will asymptotically approach 100% as we ascend. Is speciation possible in such circumstances?
Isolated populations could come from space colonies, geographic isolation from war or extreme climate events, rich people with exclusive genetic upgrades, cyborg implants that make it possible to only reproduce with other cyborgs. Just off the top of my head.
If you're less patient, give it enough time the old fashioned way and homo sapiens as they are today would eventually not be able to reproduce with their descendants. Genetic drift.