Because fans like to overreact to their teams' successes partway through the season, here is...
The Case for 10-0:
49ers at Redskins: The 49ers win this easily. Although nobody is admitting it, the complete change in offensive gameplan against the Rams HAD TO be done, at least in part, because of losing both tackles and their fullback to injury. The Rams were expecting run all the way, not a quick passing offense. They were caught off guard, and were not equipped on D at all to handle it. Couple that with the fact that their offense couldn't hold the ball long enough to give the D a rest, and there was no way they were winning that game. The 49ers are depleted on offense. But they masked it well and were able to more than make up for it with their defense. They can have a merely "adequate" offense against the Redskins and still win big.
49ers vs. Panthers: The Panthers are hot, no doubt about it. BUT what they do on offense plays to the 49ers' strengths. The 49ers D can key on McCaffrey and shut down the run with their dominant front 7. Yeah, they'll give up some yards and some points. But I don't think it'll be enough for Carolina to pull out the win on the road. And their defense has been horrid. A merely average 49ers offensive performance should get it done. The main concern I have is that the 49ers special teams could come up short in a close game if Gould and the new long snapper don't get their issues hammered out.
49ers @ Cardinals: The Cards' QB is starting to find a groove. But even a short week (this is a Thursday game), I think the unit that will suffer the most for lack of preparation will be Arizona's offense. The SF D will suffocate them, and I predict a very one-sided game.
49ers vs. Seahawks: If things play out the way I think, we will have an 8-0 49ers team going up against a 7-2 Seahawks team. The '9ers will have some of their injured players back and will have a LONG stretch to prepare for this game, going from a Thursday game the previous week to a Monday night game against Seattle. This is almost like a second bye week. And as much as Shanahan likes to plan and play the cerebral game, I think this works to SF's advantage. The Seahawks are weaker on both sides of the ball than their current record indicates. And with Wilson being one of the few bright spots for them, I think the '9ers pass rush wins the day, while their run game wears down the Seattle D.
49ers vs. Cardinals: Game 2 vs. the Cards. This one on a short week again, but at home. I don't think the Cards have sufficient time to learn from the defeat 2 weeks earlier. I just don't think they are strong enough. And even though the 49ers are on a short week, I think them getting to play back to back home games makes it a lot easier.
If that all plays out, that brings them to 10-0. The biggest, and perhaps ONLY flaw I see in that logic is that it's incredibly hard to win 10 in a row, and any given team can do the unexpected in a game. Heck, Pittsburgh is awful, and the '9ers turned it over 5 times in that game! If that happens against, say, the Panthers, I don't see them climbing out of that hole. But I do think that they have a great shot at it. In terms of schedule, the strengths of this particular team, and other factors, the stars seem aligned to get there. After that, with their next 6 games being the Packers, Ravens, Saints, Falcons, Rams, and Seahawks, it is anyone's guess what their final record will be. But 10-0 getting ready to host the Packers would not shock me.