I don't know any Christians so I'm not sure what do you mean, but people *still* read Mere Christianity today and they still praise it. If its reception among modern Christians is overwhelmingly positive, then why couldn't a book like that be written today?

In 1952 Lewis was still able to find doctrinal commonalities among the handful of "main" Christian-types. Given the emergence and prevalence of "non-denominational" and "ideology-based" Christians today, there are no such presumed commonalities. And perhaps there are no longer even main Christian-types.