Is a sub 3:00 marathon realistic?

Hi all! Hoping to get some advice from more experienced runners here. I (32m) just ran my first half marathon in early February with a time of 1:31:24. This was after an 8 week training program through the Runna app. I want to run a full marathon at the same race next year, and I want to do it in under 3 hours… is it unrealistic for me to try to increase in distance and speed to accomplish that in 11 months?

Background: I’m not a “runner” per se, but i was a three sport athlete in high school and played a year of juco basketball, so I’ve experienced conditioning on some level through sport. I’ve been weight training consistently for the past 10 years or so and am generally in “good” shape. I decided to run a half marathon this past February and followed an 8 week program to hit the time mentioned above. At that time, i was running 0 days per week, and i adjusted my training program to run 3 days per week (between 18-25mi/week).

Is it unrealistic for me to have the goal of running a sub 3:00 marathon for the same race next year? I know that the farther you go, the harder it is to maintain speed, let alone get the marginal increases in distance/speed. Can i do it only running 3 days a week?