My theory is, Takasugi is about to hunt down Utsuro, even to sacrifice himself. But he need Tendoshu to begin with. Maybe it's for the blood, or a connection to find Utsuro since Tendoshu also have a grudge against him.
For a repay, Tendoshu is trying to regain their posession towards terrorism. I don't know by what force, since Harusame and Naraku is out of question. Well, Takasugi never cares about that. They're also gonna die soon anyway
If Utsuro finally dies, i see Takasugi dying too. The blood is gonna expired, he won't be last longer, just like Oboro. The same with Tendoshu. They know about Oboro's immortality, but not with his death (by run out of blood). They once also agreed Utsuro's deal, to give his blood as long as he can end himself without even knowing if they'll still alive or not, even if Utsuro dies.
Of course i see Gintoki and Zura to be there too. But Takasugi might be the one who ends Utsuro and every immortal shit in this manga.