Here's my bold prediction for the week. At some point in the next decade or so, some club playing 4-5-1 will introduce the bold experiment of withdrawing their forward and the new era of 4-6-0 will begin.
Partly, this move is predictable in terms of long-term historical trends We've gone from the 2-1-7 (1860-1880), to 2-3-5 (1880-1935) to 3-4-3 (1935-1956 in its British W-M version and to the present day in its more attacking Dutch version), to 4-2-4 (1950-1960) to 4-4-2 (1960 - present day) and even to 4-5-1 (mostly in the past decade, mostly in England).
Some people assume that the increasing ratio of defenders to forwards is the sign of an increasing negativity in the game. This is only partly true. Yes, defending has taken on more importance, but only because attacking play has become so much more refined.
Another key historical trend is the increasing fitness levels of players as a whole, which permits players to cover much more ground in a game (the average footballer in 1970 ran 3 miles per game - it's now up to about 6...this is how Johan Cruyff and Socrates could both be footballing giants while maintaining pack-a-day smoking habits). Put simply, goals don't have to come from cherry-picking forwards, they can as easily come from surging midfielders.
The third important trend is that midfielders themselves are - in a classic example of late-capitalist production modes - becoming increasingly specialized in their roles. The division between wingers and central midfielders has always existed, of course, and there has always been a difference in style between the more attack-oriented "wingers" and the more defensively-oriented "wing-backs" (although the latter are a seriously endangered breed - since the popularization of the overlapping full-back most have been converted into defenders in the Ashley Cole/Dani Alves mode even though they would probably play as well or better in midfield, rather as Emmanuel Eboue is doing this season at Arsenal).
But now we have a plethora of roles: the deep-lying "shield"/ballwinner (e.g. Makalele or Gattuso), the central attacking trequartista or "number 10" (e.g. Totti), the hard-running dynamo or "watercarrier" (e.g. Hargreaves), the cut-inside winger (e.g. Pires), the long-pass specialist (e.g. Pirlo and possibly Beckham), the short-pass specialist (e.g. Fabregas), the deep-lying playmaker/"number 5"/"quarterback" (e.g. Riquelme).
None of these are new positions, per se - each of them has existed to some degree somewhere in the world for decades. But the globalization of the game in the 1990s (or, more specifically, the influx of a vast array of international talent into the Spanish, Italian and English leagues) has meant that a lot of these styles have mixed and converged for the first time in the past ten years and this is producing some new possibilities for the game. The Argentinian "number 5" position, for instance, is almost unknown in Europe: but the arrival of Juan Roman Riquelme has opened a lot of people's eyes to the possibility of that type of player. Trequartistas are common in Italy and Portugal but still haven't completely caught on in England (think Bergkamp playing a little deeper or Scholes playing a little further forward).
Anyways, with all these new bustling creative midfield options available, do you really need a striker? Why not play with two ballwinners behind four attacking midfielders (two central, two wide), all of whom have license to surge forward at will?
There are some obstacles, obviously. Six in midfield is pretty crowded and does not have a glorious history (Steve Sampson famously and disastrously became enamoured of the 3-6-1 in the 1998 World Cup and the Americans came home after three straight losses). Not having someone high up the field reduces the ability of defenders to play long balls (though not everyone would see this as a bad thing).
Obviously, a 4-6-0 would require a certain fairly specific mix of quite talented individuals playing a high-tempo pass and move game with a lot of position-swapping. But I'm fairly sure it would be successful simply because it would create chaos among opposing centre-backs who would no longer have anyone to man-mark. A similar ploy by the Hungarians in 1953 (dropping one attacker - Hidegkuti - off the forward line by a few yards) resulted in England shipping 13 goals in two games because none of the admittedly none-to-bright Englishmen could figure out how to mark deep-lying attackers.
The team to do it? Possibly the Brazilian national team, possibly Arsenal. The squad that played in Prague this week was pretty close having the right combination of talents to play a 4-6-0...if van Persie had played a little deeper we might have seen the birth of something quite interesting.
Forwards will ever be eliminated completely because they represent individual flair and brilliance more than any other position, but they will become optional for some teams. Squads that prefer an athletic, attacking, intelligent, collectivist approach may find that leaving one or two men upfield all the time is a bit of a waste. 4-6-0 will be their formation of choice.