To play devil's advocate: can anyone point to a year where Bryce Harper was the difference between us making the playoffs or not, or advancing in the playoffs or not?
To cut to the chase - you cannot because it hasn't happened. His best year (by far) was a year we didn't make the playoffs. In the years we have made the playoffs we still would have won the division with an average player in his place. We've never advanced in the playoffs, despite (in some cases, partially because of) his performance.
So I think the reality is the Nationals should look to trade him if they don't think they can sign him long-term. They'll likely get back a nice haul of prospects, and will still be among the widest favorites to win their division in MLB, even without him. Maybe that won't happen for any number of reasons, but that's probably the smart move.
Bryce and Max not being fully recovered from injuries and being shells of themselves was probably the biggest reason we lost this year. Strasburg, Ramos being out and Bryce sucking from Aug/Sept through Oct probably cost us last year. A healthy, mid-season form, Bryce Harper would be invaluable in the post season. We saw that once, but he didn't have the supporting cast that year.
I don't know what was going on with Harper last year, but this year was just a freak thing. I think theories of players being injury prone in general are often overblown, especially when they are all unrelated things. But, I guess that would be the biggest risk of signing Harper long term.
How much is one year of Bryce worth in a trade anyway? I'd guess not as much as many people here would guess. Is he actually worth more for a full year than a deadline rental?
I agree with the above comments that he's a huge star. Ask 12 kids on any of my son's past few little league teams in Richmond who their favorite player is and at least 9 of them will say Bryce Harper. Bryce Harper at bats late in a tight game are about as excited as Nats Park gets.
I bet they end up going with something like the player option contract mentioned above. I bet it is more like 2-3 extra years before the player option kicks in though. Bryce has got to realize he is risking a lot of dough by not signing anything this summer either. If he goes and tears his ACL in the summer, then he's left signing a one year deal needing to prove himself. I have to think the Nats would at least put 250-300 million with player options on the table.