As a niner fan, believe me, I feel your pain.
Alex Smith looked really sharp vs the chargers first team defense in the 9ers final preseason game of the year. This is obviously just a thing he does every now and then to tease the fans into thinking he could be a decent QB, but still worth noting. Im expecting him to do well at home against the seahawks in the opener too. The real tests will come when they go on the road and face teams that are worth a shit, at which time he will inevitably crash and burn like he always does.
Yeah, I've seen a lot of similarities between the Phins and 9ers over the years. Both teams have shitloads of talent, but are an average QB away from being contenders. It sucks, because both teams have elite players all over the place, but without a QB they are hopeless. At least Henne has a shot to become decent, as often times a light turns on in a players head during their third season in the rotation or starting (Henne is going into his 4th season, this is his third year of actual playing time) especially at QB, but I'm not holding out much hope for him. If I were a Niners fan, I would want Smith gone yesterday. He is irredeemably bad, and the team is still too good to get a top QB pick (no Andrew Luck for the 49ers).
This is Henne's final shot to prove himself. It does happen on rare occasions (Drew Brees anyone?), but you cannot count on it. The Dolphins should have drafted a QB at some point this year. In fact, I believe that any team without a proven QB should save a lower round pick at the very least for one. While I agree with Axl that teams with strong defense have a better shot of doing some damage in the playoffs (look at the Jets, crappy offense but outstanding defense), left tackle and quarterback are the two determining positions in this league. To sustain success over a long period of time, a team absolutely needs a QB (I know the Ravens were cited, but they faded from actual championship contention for a long time after that Super Bowl), and a great left tackle to protect him. Those are the two most important and rare positions in the league. LT is easier to evaluate at the pro level, so elite LT's are almost always off the board by the time the middle of the pack teams make their pick, so unless there is a sure thing at QB like an Andrew Luck or Sam Bradford, it is essential to take the LT instead of the risky QB pick.
Just to cite how important the left tackle position is, look no further than Mathew Stafford. This kid has the tools to be really good, but because the Lions have a total aversion to making the sensible pick (yeah, their defensive tackles will be the best in the league, and that is important, but they are not protecting their most important investment), he is likely to go the David Carr route, where a QB becomes too traumatized by the amount of hits he takes to improve. Additionally, not only do left tackles have to be around 6'6 310+ pounds with quick feet and the absolute correct hip proportion, they are expected to be at least as smart, if not smarter, than the quarterback himself. I know that tons of people on BL already know this, but casual fans do not realize just how intelligent you need to be to play offensive line in the NFL.