If they do appeal the decision, my guess is that they go with a full season suspension. Ideally, the league would like to accept the recommendation as this is the first case decided by an agreed upon arbitrator and they'd like to deflect some of the criticism that Goodell, who works for the owners, hands out uneven justice. If they are upset enough with the decision, IMO they go for a full season suspension.
It's true that Worthlessburger got only a 6 game suspension (later reduced to 4), but the difference between him and Watson's situation is that Worthlessburger didn't have 24 accusations, Worthlessburger had two.
The Robert Kraft effect is a tricky one. The problem the league had with Kraft is that there was no evidence. The video of him in the massage parlor was ruled illegal so they couldn't use it in their investigation and Kraft denied any wrong doing. With no evidence to contest his claim, they couldn't issue any discipline. If Kraft had taken one for the team and admitted to soliciting a prostitute, they might not have found themselves in the predicament they do today.