EDIT: So it's understood, since the damn title is misleading (teach me to write this when i wake up) this post is why the NFL would likely pursue a lockout over the other possible scenarios regarding 2011 if no CBA agreement is reached.
The CBA expiration and the last labor dispute
The 2010 season is considered the final league year in the current CBA, under revised rules. March 2011 is when the final year expires, and so the owners cant just decide to avoid negotiation.
Look at the last labor dispute as a good example of the course of what may occur if no new CBA is reached. In 1987 when the last CBA issues arose, the league enacted what they called the post-impasse rule when the CBA expired and as a result will get to set wages, rules, and terms based upon the last offer to the NFLPA before the deadline (as required by US Labor laws). This means, that whatever they offer the NFLPA last (however ridiculous) will become league rules given US law if the league wants to continue to operate.
The players have two options in this case. That's to strike or decertify. Originally I thought the players would strike, but I've changed my position on this and think they will decertify. Striking means losing all wages for the players, but doesn't allow the league to make nearly as much in revenue. Both in TV and ticket sales.
Most people think the players would prefer to decertify which means that they would continue play in the NFL under the post-impasse rules while the NFLPA seeks legal means to bring anti-trust cases against the NFL (what Upshaw did in 87). For some reason, a few pundits (who I think are stupid which is why they are in the minority IMO), think this works in the favor the league. It doesn't IMO.
The league may not have as many issues lined up against them when the players were fighting for free agency in 87, but they have a lot more to lose. The majority of profit in the NFL comes by way of TV contracts. This has already been an issue for the NFL and U.S. Congress. In the Patriots undefeated regular season (07), the last game of the year was scheduled to be on only the newly formed NFL Network exclusively. After impassioned contact between constituents to law makers many US Senators contacted the NFL and said they would ensure a revisit to U.S. anti-trust laws regarding NFL TV contracts if they didn't play the game more widely. The NFL immediately announced that the game would be broadcast nationwide on both NBC and CBS.
This is what the NFLPA would likely attack.... TV contracts. There are other anti-trust issues they could use. The NFL hasn't released its profits and income to the public in a very long time. If those figures became public, opinion could sway against the owners. This is bad because the owners would like to pursue anti-trust exemptions for TV like baseball currently enjoys. That becomes unlikely if public opinion is not in their favor when congress is called to action. The NFLPA would also undoubtably look at the lack of use of poison pills as collusion between owners, something the US courts deemed legal in NFL contracts. However TV by far is the most costly issue. The NFL will not chance having their exclusive rights to every NFL game put in question. They would preempt this with a lockout. It makes much better sense to lose revenue for one year then possibly lose the majority of it for years and years to come. Hence why the NFL hires the man who was responsible for the NHL lockout, Bob Batterman.
Other Considerations and Impressions
However, remember any such anti-trust issues could land in the NFL's favor, and would take at minimum five years to be played out in court. Also remember, if the players strike the other issue for the NFL is that college football is a much stronger force then it was in 1987. While some people would continue to look to the NFL, more casual fans would likely watch the more competitive college games as a retreat from "talent-less" NFL games.
Also consider this. The NFLPA hired DeMaurice Smith as executive director because he was looked at having a tough stance on upcoming negotiation. Goddell favored Troy Vincent because he was seen as being able to find more middle ground on issues. The NFLPA is obviously taking a hard stance, and the NFL is matching.
So a lockout favors the NFL. It puts the players in a financially compromised situation. They make no income while the NFLPA pursues anti-trust issues. The players won't wait five years. Talent fades to fast for these guys and the money is to good. In that situation, the NFLPA would be under tremendous pressure from the players to find a solution. If the NFL does not lockout, the players can continue to make money by decertifying while the NFLPA seeks anti-trust issues which puts the pressure on the league. IMO, if there is no new CBA by March 2011, there will be a lockout. I however do not anticipate this. A CBA resolution benefits everyone, even if each has to make concessions they find hard to swallow. There's just to much money on the line.