Many, if not most, firms have converted to electronic letterhead. The advantages to this are many:
● The firm saves significant amounts of money by not having to pay to print letterhead.
● When you change or redesign letterhead, the process is easy and you do not have to throw out the old letterhead.
● You can set your templates and other documents to pull in a single letterhead file, so that when you change letterhead you only need to change a single file.
About the only disadvantage is that you lose the ability to have embossed letterhead. However, in an electronic age this is not a significant disadvantage.
Usually, you already have, or can easily purchase a font that matches your existing letterhead closely if not identically. Failing that, you can always scan existing letterhead and insert it in documents as an image.