If that's the case, why isn't someone making billet flat-tappet cams that could possibly eliminate the problem of wiping the lobes of cast flat-tappet cams? 

Had a conversation yesterday with my grandson, who is familiar with CNC machining operations.  He says that machining cam blanks, or finished camshafts is within the possibility of CNC machining fairly easily.  Current  camshaft  grinders could grind their profiles just as easily as they currently do with their equipment.  So all is not lost except possibly current prices..

John - "The Hoosier Hurricane"

In this day of computerized machining, a cam could probably be made from a piece of round bar, but the cost would be high unless a grinder could make a large quantity of them.  Refurbished old cores may be able to keep us going for a while.

John - "The Hoosier Hurricane"

Thanks for posting. I kind of saw the writing on the wall. It might be a good idea to buy a new cam while they last and hold onto any good candidates for a regrind. Considering that many engines that were originally equipped with flat-tappet cams can be retrofitted with roller cams & lifters, it's not likely that a company will step up to continue casting flat-tappet cams for the rest of us. 

This is bad news for us Y block guys since we have no other options. I pulled this of the FE Forum

Discussions with several folks at PRI indicate that the days of the flat tappet cam - as we know it - have come to a close.
The only source for cast cam cores - CWC Textron - has apparently stopped shipping castings
A high defect rate, coupled with a large OEM contract for other products, has forced a decision to step away from camshaft casting
Unless/until someone finds an alternate source -- flat tappets are going away soon.