First here is a quote from the BBWAA about voting for the MVP:
Dear Voter:
There is no clear-cut definition of what Most Valuable means. It is up to the individual voter to decide who was the Most Valuable Player in each league to his team. The MVP need not come from a division winner or other playoff qualifier.
The rules of the voting remain the same as they were written on the first ballot in 1931:
Actual value of a player to his team, that is, strength of offense and defense.
Number of games played.
General character, disposition, loyalty and effort.
Former winners are eligible.
Members of the committee may vote for more than one member of a team.
You are also urged to give serious consideration to all your selections, from 1 to 10. A 10th-place vote can influence the outcome of an election. You must fill in all 10 places on your ballot. Only regular-season performances are to be taken into consideration.
Keep in mind that all players are eligible for MVP, including pitchers and designated hitters.
Recognize the last line that makes sure voters know that pitchers and designated hitters are eligible for the award.
As far as where it is heading, there is nothe short answer is "nowhere." Baseball and its writers especially are very stubborn in the way things are done. You will notice in the quote above that the rules have remained the same since the first ballot in 1931. Some media and fans have called for pitchers to be ineligible, but I have not heard of this catching much momentum (especially with the writers/voters).
Pitchers rarely win the MVP award. Since the Cy Young was introduced in 1956 pitchers have won the award 11 times (including Kershaw). This link lists the pitchers to do so and their outstanding stats for the year.