。
If it were me, I'd just watch how things unfold, though.
Literal
I [if-だったら] course-of-events [object-を] watch-over probably [but-けど].
僕だったら ('if [it were] me') is the 'in your shoes' hypothetical. 成り行き ('course of events, development') from 成り (from 成る 'to become') + 行き (from 行く 'to go'). 見守る ('to watch over, to monitor') is a compound 見 + 守る. The trailing けど ('though') leaves the opinion tentative. Classic gentle advice-offering frame.