Seems like we're all over analyzing the playing time issues. Sure it'll start off with Kirk/Jansen/Belt splitting time at DH but in the end it'll be the best player for the position.
Their performances will determine how much they play so whoever starts off slow will see their playing time drastically reduced. This is all assuming everyone will stay healthy, which we know isn't likely.
It is great to have internal competition between expected above average players. No more Zimmer's/Tapia's where we expect suckage from the start.