You have hit on main points for this Test match. It looks like draw is very likely about 70% and I agree that especially if Sri Lanka does not get big lead and Bangladesh bats today. Big question is whether Sri Lanka can not only catch up but also get good lead maybe 200 runs or more which would really pressure Bangladesh. But Bangladesh batting can be unpredictable so even with two days left and draw looking probable sudden batting collapse could lead to unexpected loss. So Sri Lanka needs to bat well to set tough target and Bangladesh needs to avoid any batting failures to either draw or even win. We will have to see what happens with Sri Lanka next 128 runs and how they score afterward.
It was expected that Sri Lanka would bat well on this pitch. I have always seen Sri Lanka perform well on the Galle pitch. However, I was surprised by Bangladesh's batting. Bangladesh lost 3 wickets for just 45 runs. 3 important batsmen of the top order were not batting well. Even then, Bangladesh was able to collect a big 495 runs.
Among the Sri Lankan batsmen, except Pathum Nissanka, no other batsman could survive at the crease for a long time. Pathum Nissanka played a great innings of 187 runs. Now Sri Lanka's collection is 379 runs for the loss of 5 wickets. Sri Lanka lost the wicket of Dhananjaya de Silva at the beginning of the fourth day. Today is the fourth day but two innings are not over yet. Without a doubt, this match is going towards a draw.