Now, resolving the problem has become more difficult. Ukraine will take a tougher stand and neither the EU nor U.S. will want to be seen as establishing a 21st century "Munich" moment. Russia is more deeply invested and Putin, who abhors weakness, will not want to be seen as making any meaningful concessions, especially as it has been widely reported that Russian military members have died in the conflict. Moreover, Russia stands to gain not just possible territory or influence/greater capacity to project power, but also the loyalties of ethnic Russians and even population if Russia annexes southeastern Ukraine. The population issue would help mitigate some of Russia's demographic pressures related to a general population decline, though there was recent stabilization with a modest increase. Whether that stabilization is temporary remains to be seen.
Overall, things are evolving toward a high stakes standoff. With room for maneuver narrowing, the risk that the standoff could be of a fairly long duration are increasing. That still may not be the most likely outcome, but it is no longer a low probability scenario.