I was actually looking forward to the expanded playoff too, given the shortened season.
It will be interesting to see how many players really choose to sit out. Would they still get their service time if they did that? I suppose that doesn't matter to anyone who is already out of the arbitration years anyway. Things will also get heated, I'm sure, with regards to eligibility (players whose wives are pregnant or have otherwise vulnerable family members).
For all intents and purposes the entire league will have had almost a year off (9-10 months without playing a real game) so I'm don't know if sitting out what will be just 10 weeks will reallly have that big an impact on the average player. If you're a little older (as most players with that option would be) or coming off an injury (like Cutch) it's a tougher call. In some cases the rest might do you more good than not, especially with risk of injury if you play.
At the same time if I'm Roman Quinn or Jay Bruce I show up for work, once they get hurt again it's free money.
We'll be 30 games into the season before anyone will be sharp (but everyone's in the same boat). Getting hot and staying healthy will really be a huge factor come October. If some star players sit out it could also affect which teams are truly the favorites compared to when things were normal.