The big problem with that, of course, is that Warehouse 13 Wells has VERY good reasons to want to change history - if she had a time machine that could actually change anything (Warehouse 13 has time travel of a sort, which she invented, but you can't alter history, not even small details) she'd use it herself, and if she succeeded she'd erase all her reasons for involvement in events in the 21st century.
That doesn't rule out her appearance, of course, but the character and her motives would be very different to what we see in Warehouse 13.