Sure. But at the same time, it should be said that already by 207 IOTL Rome was actually experiencing something close to a manpower shortage (Latin allies refusing to send more recruits for example). Add a few changes, Rome losing the citadel of Tarentum, maybe the siege of Syracuse dragging on longer, or far less success by Scipio in Spain, and the situation for Rome by 207, already much closer to disaster than is popularly believed, is immeasurably more bleak. So having another sizable army march into Italy and one slip up-Hannibal being alerted to Nero's gamble for example, and another Roman army destroyed might be enough to force Rome to the negotiating table.
Punic names are like that "Ha, Ha, Ha" scene from My Fair Lady and that ends with the Audrey Hepburn character setting the crib sheet on fire, so at least you aren't doing that badly.
I have tried looking into the manpower situation as best I am able and I think the bigger 'problem' was by 207 the Roman Commonwealth already had something north of 200,000 men in the field, this was not a case of the Beadle saying to Oliver Twist "You want more?" but instead the allies saying "you really don't want another wah-fer thin mint" to the Pythonesque glutton.
I am sceptical of Hannibal's ability at this stage to destroy another Roman army. Largely for reasons I have stated above. I also think that to beat Nero to the Mataurus is going to take a miracle or air lift. Nero's march was deliberately by a much smaller force which also took advantage of the fact it was moving through friendly territory so that it did not need to take supplies with it. Hannibal simply cannot move in force that quickly. To beat Nero and/or Livius to Hasdrubal Hannibal basically needs to get the letter.
That said we do need to recognise the stretch factor and that if Hannibal is focused on detaching or at least laying waste Roman allies he might bring matters to a relatively positive conclusion. Perhaps trading leaving Italy for a Roman withdrawal from Spain? I confess to being a little unclear as to Hannibal's goals, the closests to an existing out line would seem to be his treaty with Philip V of Macedon which appeared to envisage the complete conquest of Rome however that may have simply been bravado to encourage the Macedonian in and perhaps leave the Carthaginian an out on pay back.
I think that a Hannibal victory scenario really does rest on his goals. Hasdrubal would have improved his ability to continue to operate in Italy immensely as one of the limiting factors by 207 BC was that he had not the troops to keep both an effective enough field force sufficient to make the Romans wary and find garrisons to cover his widely scattered allies. Yet the problem of Hasdrubal's arrival is that it signals that Scipio is soon to be free to operate in another theatre too. Now Scipio was probably right the best place for him was Africa but even had he instead been brought back to Italy that adds yet another Roman army of experienced veterans to contend with.
That likely gives Hannibal a year to make the Romans think considering terms is a goodly notion and (critically) make them an offer they can accept before he ends up in the same slow spiral of encirclement that followed Cannae and the defections of Capua and Syracuse.