Could this be a sign of a future stroke middle cerebral arteries: there is an early trifurcation of the left mca there may be minimal irregularity of the m2 segments and right m1 segment?

This is an anatomic variation and no predictions can be made on this basis alone. Best is to followup by your doc as per your past history or evaluation.

You have a congenital vascular variation that is unlikely on its own to cause a stroke. But add in risk factors such as diabetes, hypertension, high blood lipids, and elevated homocysteine, if untreated, you might be susceptible.