Depending on how the free agents rules turn out, and depending on who you listen to, there are between 600 and 900 NFL football players that will be free agents whenever it starts. Yes, it will start. You see, it has to. Those 600 to 900 players do not have a contract or a team to play for. Each one who can find work will find work before the first game of the season is played. The first game of the season can not begin until the new league year begins. When the new league year begins those 600 to 900 guys can begin looking for work.
Now, depending on how long the lockout goes on the more critical it will be for teams to re-sign their own guys, as they know the plays (where guys going to new teams will not). Of course, a few teams have new coaches so re-signing the former players on those teams may not be as critical, and in fact, some of those players may want to follow their old coach if he found work elsewhere as well.
In summary, unless the NFL ceases to exist forever, there will be a new league year, there will be free agency the day the new league year starts, and there will be football again sometime after that.
Now that that's out of the way, the Lions did not fill all their needs in the draft. Most teams (probably all teams) did not fill all their needs in the draft. I believe this will be the first time that following the draft every single free agent will still be available. Usually pre-draft almost all the most coveted players are already signed leaving a (perceived) second tier of talent being available. That is what most fans are used to as well. This year it's different. Teams know exactly what they need to begin the season, so certain players will be fought over in what could be some very large contract wars.
Somehow in the middle of all that, the Lions need to come away with a few players to round off their roster. The pessimistic fans will believe the Lions won't find anyone, won't go after anyone worthy of going after, or that players still do not want to come to Detroit. The optimistic fans will believe that every household named player is an option, will want to play in Detroit, and will do so for a reasonable contract or that the Lions will or should gladly overpay for anyone.
The reality is, the Lions will look for players who fit their schemes (or as they say, fit what they are trying to do), and they will look for players who are likely to be worth what they are asking in terms of a contract. There could be some trades, some players could get claimed off waivers later, and some of the Lions own free agents may decide to stay in Detroit. My feeling is that in free agency the Lions have already identified a few players they would like and will attempt to sign them if they can... but if they can not... they will proceed with pretty much who they have. I also have a hunch that there are at least two players that just happen to fit in at LB and CB who will sign a Lions contract. Who? Why? Can't say... it's a hunch.
In the meantime, all we can do is wait. Wait for the two sides to finish gaining (or losing) their leverage in court to restart the negotiations for a new CBA. In the end, the new league year starts when a new CBA is agreed to or when the courts order them to start it. That order however can not be without rules, rules as to how to handle free agency, minimum wage, and all the rest of the details that have to be resolved before the first contract can be approved at the league office.
How long will we wait? I'd say there is a 5% chance FA starts in May, a 25% chance it starts in June, about a 40% chance it starts in July, I'll go with an 25% chance it starts in August and 5% it starts in September or later.
As for whether free agents will be 4 year players or 6 year players? I'm going 50-50 there.
When you look at free agent lists, remember the Lions aren't going to engage in large bidding wars and whoever they do contact when they are allowed to has to be a player that fits their roster, both in scheme and need. Players that used to play for Gunther or Schwartz might have an edge over guys that have not (and I did say "might"). That's all I got for now, and as usual, I reserve the right to be totally wrong.