Price erosion will happen from 2026 for lenalidomide as various generic companies compete with each other from 2026 as the patent expires. Until 2026 no price erosion since there is no competition, there is just celgene until then. You guys just don’t get it, do you? May be I did not explain well, I am terrible at that… 
This scenario is different folks - this is not like a generic company entering the market and the price collapses…
In very simple terms (I am assuming no price increase for lenalidomide between 2022-2026)
2022 - celgene gets $100 from lenalidomide, Celgene shares $7 with Natco from March, Alvogen $5 (may be from September 2022)
2023 - Celgene gets $100 (Natco might get $12 - just my guess), Alvogen, Dr Reddys and others who have settled with celgene will get their share as per their agreement)
2024 - celgene gets $100, Natco $18, Alvogen, Dr Reddys also get their share
2025 - celgene gets $100, natco $24, others also get their share
Note celgene is losing gradually between 2022-2026 as per the terms of their settlement with the likes of natco
2026 - patent expires, market open for generic companies, one company might get exclusivity for 6 months, after that price erosion will be severe >90%
No more comments from me about this topic.