Aem form submission to Marketo

you can capture the form submission button click in javascript and do the submission by code and show the success/thank you message in place of form. Below is an example.

$('.marketo-form').on('click', '.mktoButton', function(event) {
   event.preventDefault();
   MktoForms2.whenReady(function(form){
      //code to check values in form fields
      form.submit();
      form.onSuccess(function(vals,thanksURL){
         form.getFormElem().hide();
         $(".marketo-form").hide();
         $(".thank-you").show();
         return false;
      });
   });


});