I see this is your first post. Welcome to the HSBBW.
There is no definite answer to your question but for sake of discussion we can address velocity and the draft. Velocity is only one portion of the total package professional scouts look for in a pro prospect. Your current velocity is more than enough to be drafted in the top five rounds. On projecting velocity: I have heard some indicate that a pitcher’s velocity normally increases about 3 mph per year during his high school years. You indicate you “have hit” 85 mph but that probably not your average FB. Take your AVERAGE fastball velocity; add three miles per hour, per year, during the high school years. If this rule of thumb holds true with you, you can have a fairly good estimate of your velocity as a senior. Allow me to give a little advice. If you focus ONLY on velocity, you will fail to develop as a viable pro prospect. While velocity gets most of the attention, there is much more to being a great pitcher.
Best of luck,
Fungo