With the series of recent NCAA rule changes rosters are capped at 105 ( 85 scholarships in the SEC + 20 non-scholarship) , in that ruling they also grandfathered all non-scholarship players who were currently on a roster, so you may find the current roster over 105. As those grandfathered players graduate, they will come down to 105, so basically its 20 spots. If you assume a normal distribution, its 5 per year, then factor in a few preferred walk-ons ( legacy kids, high potential who choose A&M path, specialist) you are really looking at 1-2 spots per year. When open walk-ons tryouts were a thing, you would see between 100-150 kids show up, so figure 1-2% chance of making it, but there is a chance.