HTML Website

Hi --
Many years ago my website came to life in the HTML format. The website is not small. It has 160 pages. FYI: I am the largest and best know restorer of antique pump organ in the country and receive emails, text messages, and phone calls from all over the world. 
All the search engines rank my website No. #1 for the unusual service and information I provide. Now, so there can be no misunderstanding, I know beans form shoelaces about website construction, coding, and all that stuff. Over the years someone else has done all that. 
But that was then and this is now. The website has not been altered cosmetically in any way for many years. Every now and then some copy or maybe a photo was added and that's pretty rare. 
Well-meaning people tell me I should blow up my website and move everything over to WordPress. What I feel I should do is try and track down a real HTML sharpshooter and have them clean up the website. 
I'm told HTML is old, out of date and nobody uses it anymore.  
Any thoughts?
 Rod Fudge
"America's Restorer of Antique Pump Organs"
pumporganrestorations.com