I wouldn’t count on that. I don’t want to sound pessimistic, but Remote Play and Second Screen operate very differently. Technical standpoint aside: Second Screen allows you to control the console through the app ánd controller at the same time. Emulating the Second Screen app therefore is practical in controlling the console. Remote Play acts like a Dualshock/DualSense controller. This means when you connect through Remote Play, your controller will disconnect. Making it less ideal for controlling your console.
Ofcourse, the PS5 is just released and a lot of features from the PS4 are still missing as of now. So my bet is all will be possible again sometime in the future. We just have to be patient and hope Sony will release feature updates to bring back missing PS4 features to PS5.