I went for a 30 mile round trip this morning. After a couple of miles I decided to ride along the Taff Trail for six miles to Pontypridd because of the scenery. I have never seen so many cyclists on it; families, couples, single riders of all ages. Great to see but not so great to ride through so I stuck to the roads the rest of the time, nearly all road cyclists, and a lot more than I used to see a year ago.
I volunteer at a community bike workshop that sells used, renovated bikes and we cannot keep up with demand from people who want to try to get back into cycling for leisure or local commuting.
The current boom may not be here to stay, but it would be surprising if it was given the strange circumstances. There will be people who drop out of cycling after trying it out but that has always happened and I am certain that it will result in a large number keeping it up from the high number of new cyclists.
You never know, some of them may even turn into "proper" cyclists like everyone on this forum.