To start, I'm basing this question off of the card art leeks from the Open where it appears SY is indeed getting more bounty support, and MO getting more relic support. At least the art would seem to say so. Also, this poll will only have two options, as the obvious choice that could be added could be based around better balancing, which I think most already agree that is a given regardless of how the expansions are handled.
With the new expansion format, it seems that a lot of people feel like the meta is becoming stale for overly too long. The expansions for each faction are based solely around a specific archetype, while support for other archetypes become power crept due to the new OP cards. Maybe it is just me, but I feel like the thought of even getting more relict cards, or bounty cards, is just making me uninterested in the next expansion. The only thing I am even looking forward to is the card art
With the new format, this makes it feel like the staleness of the meta is dragging out further and further most likely because of the more difficult method of trying to do proper balances with older cards, while making sure the new cards aren't just a complete wash. It's hard to nerf or buff something when the entirety of the new support for an archetype won't be released, and then played out fully for a 6 month period. Compared to the previous expansion format where the entirety of the expansion dropped at once, and this allowed the devs to balance what needed balance just after a month or two of seeing the results as a whole. Well, not they don't get those results, at least whole picture wise, until 6 months out.
This is just an opinion but I feel like if this method of expansion continues, then each mini-expansion would be best served as supporting multiple archetypes, rather than having all 3 expansions based around a single one for each faction. For example, instead of the already really strong relicts, bounty, ST spells, and so forth now getting even further support for yet another expansion. We could have had several archetypes get support, but just have fewer cards for each said archetype receiving support. Let's be honest, do relicts really need even further support? Probably not, as it is just going to lead to the already released relict cards getting nerfed even harder most likely.
The idea of smaller support for multiple archetypes would theoretically help ease the burden of proper balancing on the developers end also. As we saw earlier this year with leader cards, and even solo release cards like Madoc and Wanderers, there doesn't need to be a lot of cards to help bring an archetype back to being competitive.
Now with all this being said, there is an argument that can be made that factions like SK and NR still need further support for the archetypes being expanded upon. But at the same time, there could be a counter argument that some proper balancing of already established cards that synergize with those factions specific expansion cards could make them competitive. Unused cards that have fell out of rotation, can then be buffed to make those archetypes stronger, or reworked entirely similar to the way several of the NR older cards were reworked to help support the cooldown implementation.