Won't happen, existing seals were converted to meds with U10 to avoid flooding the game with these "elite" items (the game was flooded by other means unfortunately), so we now have many people with 100k+ medaillons and marks, and allowing a reconversion would see similar problems.
Originally Posted by Shrelana
You can get seals from level 85 raids on any tier, or from challenge quests in level 85 3 and 6-man instances. You can no longer get seals from completing instance deeds.
You can only get seals in group content - I believe 6 and 12 man instances only - it was 3 mans up until one of the latest updates.
Used to play: 85 Champ / Captain / Runekeeper / Guardian, Guild Master of everything but cooking.
Playing now: Hellcat / King Tiger / GW Panther / IS / KV-5 / M4 Sherman and more