If the Conference League winner also finishes in a Champions League/Europa League spot, they just qualify for the respective competition as normal. If they finish in the Conference League spot, they go into the Europa League and England has no Conference League place next season. However, if Conference League winner finishes outside the European places altogether, then England would have three Europa League places next season. As happened when West Ham won it.
As it stands, all of the top sixteen (plus Southampton) still have a theoretical chance of qualifying for Europe one way or another.
I don’t think that bit’s quite right. Places are awarded like this ….
1. Top 4/5 in the league qualify for Champions League - (transferable status irrelevant)
2. Champions League and Europa League winners qualify for Champions League - non-transferrable
3. Next highest league position and FA Cup winner - qualify for Europa League - transferable
4. Winner of Conference League - qualify for Europa League - non-transferable
5. Winner of League Cup - qualify for Conference League - transferable
Essentially teams only qualify via European competition if they haven’t qualified for the same or better competition domestically. But if they do, their domestic place can go to another team.
As an example, if Chelsea won the League Cup and Conference League, they’d take their Europa League place from Europe and their Conference League place would go to the highest non-qualifying league position. But if they won the FA Cup and Europa Conference, they’d take their Europa League place from the FA Cup so the Europa Conference winner’s position would disappear - it couldn’t be awarded to another club via the league.
You can in principle have 11 teams qualify for Europe (7 Champs League places, 3 Europa League places, 1 Conference League place), but it needs a convoluted set of circumstances where English teams win every European competition, but all of those teams underperform domestically.