So here I go:
My version:
Dev was saved, but does not want to come in front right now. He knows and has realized Shantanu is up to something and is trying to kill him. But does not know exactly why and does not know who else is behind him. That's why when he fell, he left his watch and cell behind and parts of his clothing to indicate that he is "dead". He knows this will upset many, especially his beloved Radhika. But he has faith in Kanha and his love and knows Radhika will know in her heart that he is alive. Like Radhika said " dono ki sanse judi hui hai". I cannot live without the other.
He will return in hiding and with help of Radhika unravel the reason behind Shantanu' motives.
That's my version. what is yours?