What's the easiest method to change the namespace value using LINQ to XML?

TL/DR: What's the easiest method to change the namespace value using LINQ to XML, say from xmlns:gcs="clr-namespace:NsOne;assembly=AsmOne" to xmlns:gcs="clr-namespace:NsTwo;assembly=AsmTwo"?

Why? because:

I serialized Xaml using System.Windows.Markup.XamlWriter.Save(myControl). I want to visualize this GUI appearance somewhere else (deserializing using System.Windows.Markup.XamlReader.Parse(raw)), in another project.

I don't want to link to the original assembly!

I just need to change the namespace, so XamlReader.Parse(raw) won't throw an exception. I currently do it using regular-expressions and it works, but I don't like that method (e.g. if I have xmlns:gcs="clr-namespace:NsOne;assembly=AsmOne" inside a CDATA)

This is my serialized Xaml:

<FlowDocument PagePadding="5,0,5,0" AllowDrop="True"
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:gcs="clr-namespace:NsOne;assembly=AsmOne"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

    <gcs:MyParagraph Margin="0,0,0,0">
        <gcs:MyParagraph.MetaData>
            <gcs:ParagraphMetaData UpdaterParagraphUniqueId="1" />
        </gcs:MyParagraph.MetaData>
        <Span>some text...</Span>
    </gcs:MyParagraph>
    <gcs:MyParagraph Margin="0,0,0,0" Background="#FFF0F0F0">
        <gcs:MyParagraph.MetaData>
            <gcs:ParagraphMetaData UpdaterParagraphUniqueId="2" />
        </gcs:MyParagraph.MetaData>
        <Span Foreground="#FF0000FF">some more text...</Span>
    </gcs:MyParagraph>
</FlowDocument>

(MyParagraph and ParagraphMetaData are custom types and they both exist at the source assembly and the destination assembly. MyParagraph inherits WPF's Paragraph)