I actually dont think our chances of taking the senate have increased. GA isnt a tipping state in the case of the senate; there are 4 other races that are likely to flip before GA(CO, AZ, ME, NC). Even if GA is the tipping state, its highly unlikley the combination we get is(CO, AZ, GA, GA) or (CO, ME, GA, GA).
What I do think this increases is the Ds chance for a larger majority. Both seats are likely to track similarly to one another due to GA's inelastic nature, so if we win GA we likely get both senate seats instead of just 1. So, to show the math, before this announcement to get a rather stable 53 seat majority we would have needed (-AL, CO, AZ, ME, NC, GA, IA, TX) where now due to the retirement we need (-AL, CO, AZ, ME, NC, GA, GA, IA), a much easier feat comparatively.
I don't think it's a given that ME flips before GA.