That is true, John Lane understands this - he went as far as to propose a solution that an antipope can validly appoint bishops for the good of the Church. He understands the problem of Apostolic Succession, he even admitted that if there is no bishop with ordinary jurisdiction left then sedevacantist thesis is false. Some sedevacantists try to solve it by saying that Pope Pius XII's bishops still have jurisdiction, because their resignations were to antipopes and thus were invalid and they still have jurisdiction, even though they don't know it(!).
Bosco is either ignorant of this or tries to sweep this under the rug because he has no answer to this problem, a problem which is devastating for the sedevacantist thesis.
John Lane made the stuff up as a result of faulty reasoning, and you fell for it.
The Church started as a handful, and can be reduced to a handful,
Dioceses are geographical areas carved out by a pope. They are carved out of the Universal jurisdiction that the bishop of Rome has over the whole world.
A diocese doesn't have as much jurisdiction as does the See of Rome, and a pope can limit it as much as he wishes.
A pope can remove all dioceses in the whole world, but he cannot remove the See of Peter, which is the Roman diocese.
When a pope dies, the jurisdiction doesn't disappear because it is attached to the diocese, not the person.
The books acknowledge that by divine law, a pope was once, (and can be) elected by the clergy-citizens of the Roman province.
They use no jurisdiction to elect a pope. They merely express their wish to a bishop that they would like him to be, and that man can either freely accept or reject the proposition.
The election of a pope requires no jurisdiction from any bishop in the whole world.
If Italy were nuked and all citizens died, a traditional priest could become a citizen there and make it his domicile. If he made a phone call to a man validly consecrated a bishop in South America who was a wandering bishop without a diocese, and that man accepted the proposition, then the world would have a pope, who could once again wield his Universal Jurisdiction around the world.
It's just fear-mongering to throw around this "no apostolic succession" threat. It makes people feel that someone is not a Catholic, or shouldn't be providing the necessary Sacraments. Historically there were wandering bishops without jurisdiction or even title to a see, but they were considered Catholic and functioned to provide the Sacraments. Priests who don't have the fullness of the priesthood, don't have ordinary jurisdiction, but they are certainly "successors" of the apostles by their ordination. And, as Bosco mentioned, in an emergency, epikeia and supplied jurisdiction comes from the Church to allow them to proved what is needed.