Merging form responses

Will 4.0 have the ability to merge form responses and uploaded attachments into one pdf?

I believe you are referring to the Form Builder Version 4. Please take note that this major update is for the Form Builder's interface.

If you want to merge form responses from different forms into 1 CSV file, please use the Combine Submissions App. Here's the link: https://apps.jotform.com/app/combine_submissions. 

You may also download the form submissions into a single PDF file in the Submissions page. Please take note that this can be only done in a single form. In the Submissions page, scroll down and you'll see the "PDF" button above the Grid Report. Please click it to download all submissions into 1 PDF file.

Hope that helps. Thank you.