The regulations don't specify things either way. Bottom line with the regs as they currently stand is that if a product's manufacturer hasn't filed a PMTA by 8/8/18, that product can no longer be sold in the US, and if the FDA hasn't approved the PMTA within a year, the product must also be withdrawn. Since the cost of preparing a PMTA is six figures at a minimum, it's doubtful that very many will be filed, particularly since there's no guarantee that any will be approved at all. However, speculation is that a sealed, closed system has a better chance of approval than an open one that could be used with any e-liquid, or an e-liquid that could be used in any device.