As I may be losing Leningrad this campaign season and consider myself an intermediate player, and I've taken it in HvH, I'd say its possible. I've also seen a few HvH games where the drive got stopped dead. I think Leningrad is one of the first "slow" decisions of the game. The German player is used to flying over the steppes, smashing formations, making pockets and racing for objectives. Short of a substantial early victory in AGN, the Leningrad campaign probably isn't going to look like that - it will be series of hard fighting for everything north of Pskov, lucky to trap a few divisions and often gaining a only one or two hex rows a turn...sometimes just hexes. And that sounds really unappealing to the blitz mindset. The flip is there really aren't that many hexes from Pskov to Leningrad, and once you've reached the lake, three hexes in either direction can close to guarantee the fall. It might very well be worth prying your way forward successfully dooms the city even if it isn't until November or December.
Of course, a few bad holds, a misjudged turn or two, and suddenly there isn't much room for error. But a tighter margin and impossible are very different.
The city itself is a big win. On the VP side it isn't just VP, its VP YOU WERE NEVER SUPPOSED TO HAVE. Given the VP model challenges you to match history or beat it, you only actually need to score 54 more points than the historical Germans to win decisively. This is 36 of those points, where taking Sevastopol (which you will at some point) is 3 of them. Add on its a major population and industrial center, and provides Antwerp-on-the-Baltic for AGN, and it's a big deal. Plus, unless you win the game entire, at some point the Soviets are going to be coming back the other way. If they're starting practically on the doorstep of Pskov and Talinn, you might find the north getting quite uncomfortable in the mid to late war. And of course that shorter front may save you defensive perimeter space, but is goign to translate to soviet armies redploying somewhere else.
Weighing against that, it certainly isn't easy, and it does require a hefty commitment of forces. There is every chance you'll fail. And if you don't grab it in '41...odds are low you'll ever get it. So, work for a major advantage in the one period it might work, or send those forces somewhere they might achieve a decisive result, knowing you'll never have the shot again and might be in a bad way when the tide turns?