There have been rumors that the Premier League is discussing having a fourth and final Champions League spot be competed for in a playoff. By extension the Premier League's Europa League places would also be competed for, with at least the fifth-placed team qualifying for that competition. If the League Cup and FA Cup winners are qualified for the Champions League, though, then the proposed fourth through seventh teams that would compete in a playoff would already be assured of European competition.
A Premier League playoff would be complicated, but it is a great idea. However, it should wait a year or two before being implemented.
The last time the top four was not any variation of Chelsea, Arsenal, Manchester United, and Liverpool was in 2004-05. Of course, that was the year of the Liverpool/Everton qualification issue given their memorable win over AC Milan and before that it was in 2002-03 and 2001-02, when Newcastle finished third and fourth, respectively. So since 2002, there have only been three deviations of the big four finishing in the top four.
Which is one reason why a playoff should be held.
There hasn't been enough competitiveness in the top four to cause an issue in the Champions League qualification. For there to be a playoff, there has to be new teams in the top four like Manchester City, Aston Villa, or Tottenham.
Another reason why the playoff should be put on hold is that each of the big four has made the Champions League Final since 2002. Liverpool and Manchester United have made it twice, winning once. Arsenal and Chelsea have each made the final and lost. However, when you look at Newcastle and Everton's Champions League performance, they failed to reach the knockout stages of the competition. In fact, the best performance of a team not in the big four was by Leeds United, who reached the semifinal back in 2000-01.
The only way to justify a playoff is if an outside team qualifies for the Champions League and performs. They cannot bow out in the qualifying round or the group stage. They must reach the knockout stages, at least. To purely justify a playoff, a deep run to at least the quarterfinals is required.
But as the Premier League becomes more and more competitive, the need for a playoff will rise, and if it creates the same level of competitiveness like what we see in the Championship (where places four through 16 are separated by just 13 points, comparable to just four games), then there is no reason why a playoff should be implemented.
If a playoff is installed, it MUST be held in England. Not China, not the US, not Africa, or anywhere else. Game 39 was shot down and just because this adds more games to the schedule, doesn't mean that it should be its replacement. A simple two-legged home-and-home semifinal with a final at Wembley would be perfect. Although it would stretch out the season, it could be cut down to as little as a week and a half if you decide to have the second leg and final held in the same week.
A Premier League playoff would be good for a league that has become more rewarding of those with the big wallets. A playoff would give the team with the medium-sized wallet a chance and for that it needs to be implemented.