|From what I remember of Fort Stedman, the goal was to force Grant to contract his lines so that Lee's army could hopefully escape Petersburg, and break into the open country once more. I don't think they were trying, or were capable of, destroying City Point. I'm not sure if that's a reference to Grant's headquarters or not, but I don't see how it was going to happen.
In my personal opinion the outcome of the war had been decided when Lincoln won reelection. Whatever faint hope the Confederacy still had left by the fall of 1864 vanished at the ballot box. From that point on, it was just a matter of when it would end and how many more would be killed or crippled. That may be a little more obvious in retrospect than it was at the time, but I think a lot of folks were starting to see the proverbial writing on the wall.
But assuming for the sake of argument that Lee does somehow escape Petersburg at this time...what is he going to do? I think the goal was to hopefully join forces with Johnston's army then in North Carolina, and somehow or another defeat first Sherman and then Grant. Not to be rude, but I think that idea had about as much chance as did Chattanooga of beating Oklahoma in football the other day. That game was 50-0 by halftime, and it wasn't as close as that score suggests. Even assuming Lee and Johnston join forces, and attack Sherman before Grant can arrive, all Sherman really has to do is hunker down somewhere, if he's so inclined, and wait for Grant. Plus, I think Sherman all by himself is a numerical match for Johnston and Lee, or close to it, although I'd have to double-check that.
But they have to literally destroy Sherman's army, and do so before Grant's even larger and more powerful army arrives to help. Look at the speed with which Grant, Ord, and Sheridan ran down Lee during the Appomattox Campaign. Does Lee honestly have a realistic chance of escaping these attack dogs a couple of weeks sooner, and make it all the way to North Carolina before they catch him? And even if he does, he then has to defeat not one, but two of the Union's most powerful armies, under their two most successful commanders. One of whom has never lost a campaign, and has a reputation of grabbing his opponents by the throat and twisting. Hard.
Lee's other option would have been to disband his army into a guerrilla force. To his everlasting credit, he refused this very option shortly before surrendering at Appomattox. I don't see him doing differently anywhere else. He waited until he was finally cornered to run up the white flag, but once he did, that was it, and he knew it.
I'm afraid the Confederacy by this point in the war was out of options, and out of chances. Their economy and infrastructure had largely been wrecked, their major cities were captured, what existed of their production capacity was destroyed, their links to the outside world had been severed, their landscape had been blasted apart, their armies were mere shells of their former selves, and their citizens were worn out. It was over, even if not everyone, such as Jefferson Davis, was willing to see it.
Lee was an excellent commander and Johnston wasn't bad, but by the spring of 1865, there is simply no way they are going to turn the war around, together or separately. Lee's gamble at Fort Stedman was truly a forlorn hope. That's the way I see it myself.