Yes indeed, the Core i3-7100 processor has been discontinued. In fact, a great many of the other 7th gen Core i3 processors have also been discontinued, so your choices are limited. Here is a search that will display the specifications for the compatible 7th gen Core i3 processors that remain in Launched status: https://ark.intel.com/content/www/us/en/ark/compare.html?productIds=97125,97130.
Perhaps you might want to consider a Core i5?
Hope this helps,