The boots on the ground are not the issue, except Turkey takes care not to fire on US forces.
The air support is the issue. But what will happen when Turkey attacks our Syrian allies if US is not present? Will we fire on a NATO “ally”?
Yes, we will fire on a NATO ally. If the NATO ally is that far afield that they would be involved in ethnic cleansing, then Trump would stop it. He is no fan of NATO
I think we have lots of means of coercion over Turkey besides putting 2000 human shields between them and the Kurds