Depends on whether or not Ukraine take Kreminna and Svatove. Both town runs supply line into Sieverodonetsk and Lysychansk, and if either or both towns felt. There is no way to supply Sieverodonetsk and Lysychansk can hold. The problem rather is will Ukrainian take them? There is no strategic value for both town other than being one of the towns in Luhansk, Russia see it as the last town they need to take to complete Luhansk conquest. Ukraine don't see it so, they may simply by-pass them and attack Starbolisk instead and really try to crack Luhanksk city itself.
And current intel suggest Kreminna is going to fall in the next 72 to 108 hours, Ukrainian are already fighting in the outskirt of Kreminna, and Savtove can probably last a week or so, but Russian don't have enough troop to guard the entire line.
View attachment 884232
This is the OSINT Map on Kreminna-Lysychans front. Every Square with a X on top is a Brigade. and there are 10 Brigade stack in between Lyman and Kreminna at this moment. 10 Brigade = 40,000 men.
Last intel Briefing I have access to claim Russia have 2 divisional strengths in the area or 5 regiment in total, 2 of them were just retreat from Lyman, so their loss is uncertain, and even if those 2 divisional strength are at full strength, you are talking about less than 25,000 men.