Apple is likely to maliciously comply by allowing external links yet introducing new restrictions and guidelines that will dissuade developers from even trying.
This would be in line with their attempt to charge further commissions in South Korea and the Netherlands after being forced allow alternative payment systems for certain app categories.
Prior history from the Netherlands last year indicates that Apple offered to take 27%, rather than 30%, when payment is processed by a third party. The US judgment is compatible with that proposed practice.