Programatically switch content in a page

My current set up:

Xamarin Forms, consisting of iOS, Android, WP app and shared PCL. Using MVVM Light to keep a nice separation of concerns.

Brief intro into what I want to achieve. I want to have a Base page that has a Cancel and Next button. On pressing the Next button Content is loaded dynamically within that base page.

Content Page act as Base View

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="LogInPresenterView">
  <ContentPage.ToolbarItems>
    <ToolbarItem Text="Cancel" Priority="0" Order="Primary" Command="{Binding Cancel}"></ToolbarItem>
    <ToolbarItem Text="Next" Priority="1" Order="Primary" Command="{Binding Next}"></ToolbarItem>
  </ContentPage.ToolbarItems>
</ContentPage>

View Model for above Xaml Page

public class LogInPresenterViewModel : ViewModelBase
    {

        public LogInPresenterViewModel() {}

        private RelayCommand _next;
        public RelayCommand Next
        {
            get
            {
                return _next ?? (_next = new RelayCommand(async () => await DoNext()));
            }
        }

        private async Task DoNext()
        {
           // IN HERE I WOULD LIKE TO DYNCAMICALLY LOAD CONTENT / VIEWS
        }

Usually you would have a StackLayout etc before the element. However, on clicking the Next Toolbar Item I want to dynamically load content (that has a viewmodel).

So maybe my ICommand for my next button checked to see what the current content type was, and depending on that I would load another bit of content.

The scenario would be, the base page would load along with the first bit of content - Enter Email and Password. User enters that then clicks on next, if all ok, the content is replaced with the option to enter a security code, keeping the base Close and Next buttons at the top.

Hopefully this makes sense. I know what I want to do in my head, I just don't know how to translate that into Xamarin Forms...