Mariupol took 2 month, Severondoensk took 2 week and Lysychansk is taking 2 days. Russia tempo and logistics are firing on all cylinders. Donbass will be quickly overrun because the worse possible outcome of a defensive front is low moral and logistical confusion as ukrainian army retreat. Lysychansk had Ukranine's battle hardened troops and if they don't stand to fight, the entire Donbass defensive line will collapse. Whether Putin wants Odessa or Kharkiv, it's up to him. I can't see how a newly formed conscript army with little training can stand up to Russia army.