Negotiate with the Taliban?

I would disagree with Johnson that Afghanistan is sure to fail. The Afghan government has a lot of weaknesses but so does the Taliban. They are very fractured, have little ability for coherent action, but above all have very little appeal politically. They have failed to develop a good narrative. There claims to be fighting for Islam are undermined by there reliance on poppy as their most important cash source. The have some legitimacy fighting the foreign invader but we have done a good job of ensuring the Afghans government is everywhere we are.

That being said, our odds of success there are less than Iraq for the reasons you highlighted. Afghanistan is simply a very tough nut to crack. What Obama has done is hedged his bets. He has the right people in place, now we'll see if upping the resources available will accomplish anything.

I think the stories recently making a big deal about negotiating with Taliban miss the point and are dangerous. Getting members of the insurgency to defect or stop fighting rather than killing them has always been a part of any counter-insurgency strategy. Most of the Taliban, as with any insurgency, fight for situational reasons and it is possible to turn them. However, because they fight for situational reasons, you have to change those situational factors before you can accomplish anything. That means providing better security, effective political enfranchisement, economic development, and governance development. They won't switch sides if you simply talk to them.

Negotiating with the leaders of the Taliban, the hardcore minority, will accomplish nothing. Just ask the Pakistanis who have struck deal after the deal with the Taliban in Pakistan only to have fighting break out again and again. All they have accomplished is strengthening the grip of the hardcore minority over the rest of the insurgency. By sitting down and negotiating with them as equals, they have appeared weak and enhanced the prestige and respect due to the hardcore minority.

If It's In Time Magazine Then Truly Everyone Knows It

Time Magazine is not a very good publication (I would submit to you as evidence the picture at the beginning of the article I am about to link to which claims to show a US soldier "tak[ing] aim at a suspected Taliban hideout in the woods of Oshaky, Afghanistan" when he is clearly using his ACOG for the purpose of magnification, not target acquisition) so if they know that the US believes that a political settlement including the Taliban is the eventual outcome in Afghanistan, then pretty much all the cards are on the table. US leaders know we cannot be in Afghanistan for too much longer, the Taliban knows that we know it, and we know that the Taliban knows that we know. The point of all this knowing is that we cannot hope to achieve much of anything with the current surge.
The fact of the matter is that the Taliban can simply wait a year or two until we start to draw down before they go back on the offensive and they know it. And although I am very reluctant to draw historical analogies (especially ones that involve Vietnam as it has become cliche) I can't help but think that this surge is simply Obama's Christmas Bombing. So why waste time with a surge that the Taliban know they can wait out, that we know that the Taliban can wait out, and that the Taliban know that we know that they can wait out?
So what does this say about counterinsurgency more generally? That a foreign army cannot fake resolve. A legitimate and capable host nation partner is absolutely essential. Which brings us to the real problem for the US in Afghanistan. No Afghani institution(s) have the ability to resist the Taliban in the Pashtun parts of the country and this is a fundamental that will not change in a year or 18 months.