Dude, if they hold the Russian for 2 months in Sieverodonetsk, you are talking about a better defensive position. How long can they hold depends on two things.I think the Ukrainian army will give up lysychansk, and you think the Ukrainian army will stick to lysychansk.
OK, let's wait patiently. In a few days we will know where the next offensive and defensive war will break out.
1.) How long it takes for Russian to break out from Popasna and attack Bakhmut
2.) Sloviansk and Kramatorsk under threat.
They can probably hold that line indefinitely unless 1 or 2 break.
Again, you really should stop present yourself like a military person, because your "Prediction" is funny at best, illogical is probably the choice of my word.