Sadly, with everything I've read and heard to date, I believe the body will be found in the lake and his demise will be tried to be explained/set up as an accident which took place when he went fishing alone while waiting for his dad to return from his errands. MR has, in my opinion, overemphasized the missing fishing pole, and several times (including on the DP TV show) mentioned the fact that Dylan may have gone down to the lake. Collectively, everything Mark has said leads me to believe he is not being truthful about what happened that night, and to me, this is the likely scenario.
I haven't figured out a couple things though. Supposing this happened, how would the body be put into water deep enough to not be easily discovered without a boat? Is there an area near shore where there's deep water access - like a cliff? Secondly, to keep a body down, it would have to be weighted, but if discovered weighted, it would obviously not be an accident. This could be interpreted by some as an accidental drowning except for the weighting. Could this have been done in a way that appeared like it was an accident?
I'm glad the family has found a team/teams to help search the lake. It looks like it was partially melted by the end of March last year which is just a few weeks away.