EB2 and backdate

Just because currently EB2 applicants are not subject to the visa cap, does not mean that EB2 will be free from this cap in the future. Many immigration lawyer predict that EB2 will be subject to visa cap and be backdated soon. If someone could apply EB3 right now but chooses to apply for EB2 to avoid the cap, he may lost the priority date he could have obtained had he applied the EB3 in the first place.