Unfortuantely there is no way to lose the attachment than by using code which ads its own complexities.
You can certainly include a hyperlink in the subject or intro.
One option is to make your form smarter.
I am assuming you are tracking form state in a field for your workflow.
In your submit, set state to email, fire the email submit. Set state to pending or whatever submit to sharepoint or the saved copy.
Then add a rule on open where if state is = email switch to a special view instructing the user to use the hyperlink in the email or put the hyperlink for them in the attached form view.