Ember ContainerView

formTemplates.js

<script type="text/x-handlebars" data-template-name="firstForm">
  First form
</script>
  
<script type="text/x-handlebars" data-template-name="secondForm">
  Second form
</script>
  
<script type="text/x-handlebars" data-template-name="thirdForm">
  Third form
</script>

FormViews.js

App.FirstFormView = Ember.View.create({
  templateName: 'firstForm'
});

App.SecondFormView = Ember.View.create({
  templateName: 'secondForm'
});

App.ThirdFormView = Ember.View.create({
  templateName: 'thirdForm'
});

index.hbs

{{view Ember.Select 
  contentBinding="content"
  valueBinding="view.selectedValue"
  optionValuePath="content.id"
  optionLabelPath="content.value"
}}
      
{{view view.formsView}}

IndexRoute.js

App.IndexRoute = Ember.Route.extend({
  model: function(){
      return [
        {id: 0, value: 'Form 1' },
        {id: 1, value: 'Form 2' },
        {id: 2, value: 'Form 3' }
      ];
  }
});

IndexView.js

App.IndexView = Ember.View.extend({
  selectedValue: null,
  forms: [
    App.FirstFormView, 
    App.SecondFormView, 
    App.ThirdFormView
  ],
  formsView: Ember.ContainerView.create({}),
  changeForm: function () {
    var forms = this.get('forms'),
        id = this.get('selectedValue');
    
    this.formsView.set('currentView', forms.objectAt(id));
  }.observes('selectedValue')
});