I think segwit is a prerequisite to make LN a success. Maybe it's like this: segwit was made for like person to person, person to exchange or person to service, something which involved a single transaction. While LN covers wider range like an exchange sending to all traders that makes a withdrawal request, like a company that will send salaries to employees. So they are both needed and neither segwit nor LN be deactivated in the future.
Are you able to elaborate on why you think segwit is a prerequisite for LN success? Is that because it will limit the cost of the required transaction to open the channel for the LN? Is it because they both offer different solutions and will work well in tandem, covering both single and multiple transactions between sources?
Think of it like in a country. If you plan something big you must start small. Solve these small problems first and little by little it'll be a lot easier to solve the major problems. I'm very sorry if I can't explain it so well. Maybe I'm stupid.
