It tough to say without much more information, but a defendant convicted of a felony domestic assault crime, would be a convicted felon for life, which would preclude many employment and other opportunities. With a low criminal history score, the Minnesota Sentencing Guidelines would call for a presumptive sentence of a stayed prison commitment, with up to twelve months in the county jail (the workhouse), along with other conditions for the years on probation. With recent convictions, it is likely he may be on probation for those still; and so there would likely be an execution of a previous stayed sentence - meaning, more jail time.
Many variables will come into play, but he could potentially be facing jail time for this offense. Also, it seems he may still be on probation on his last case, so he could also be looking at jail time on a violation of probation. Every case has its own evidence, and the prosecution may or may not have a strong case against him. However, they will know his history and they may decide not to "cut him any breaks" based on that history. It is important that you son has legal representation on this case, whether a private attorney or a public defender. I wish you both the best of luck.