While a lot of the recent posts on this thread are more about International / SOO eligibility than the RLWC2021 (sorry moderators!), I'm going to throw my two (or ten) cents in on the former as I'm not aware of a separate thread for this.
I'm in the "Porque no los dos?" camp in terms of eligibility - there is no reason why RL can't have both a strong SOO series and a stronger international game. In my view, the issue currently lies in the fact that the ARL treats SOO as if it is still 1980. The world has changed significantly since then - the global economy and increased movement of people means that a last number of people have ties to more than one country and/or culture. However, the eligibility rules do not recognise this.
The current rules (or certainly those prior to allowing Tier 2 nation aligned players to play) suggest that SOO is still seen as a trial for the Australian team - which I don't think is the case any longer. Selection for NSW and QLD should be similar to that for Indigenous and Māori sides, in that International team alignment is irrelevant - the criteria ought to be solely based on where you first played [senior] rugby league (i.e., your "origin"). The different to Indigenous / Māori selection being that nobody should be able to play for both NSW and QLD given the eligibility criteria being based on "origin" rather than heritage/culture. In this vein, I'd have no concerns seeing a player with cultural ties to both playing for the Māori side one year and then the Indigenous side the next (e.g., Thurston) if they chose to do so.
I have the same view on International selection - if you have ties to two countries (I haven't looked at the rules, but that tie should definitely be a better tie than Nathan Fien initially had, haha), then you should be able to play for either and NSW/QLD or Maori/Indigenous selection should not impact that (and vice versa). You should also be able to play for both - but not in the same year, and IRL needs to be very clear on the rules about "flip-flopping" (i.e., I don't think people want to see a player play for (for example) Australia every second year and NZ every other year). For example, a player might be allowed one International team alignment change in a three year period - e.g., next year Nanai could go and play for Samoa, but would then be ineligible for Australia (or the Kiwis) for 3 years.
The key, in my view, is to get as many quality games in a calendar year as it is safe to do so - this means NRL/Super League, representative fixtures based on origin and/or culture (e.g., SOO, City v Country, Māori/Indigenous) and international games. The more quality games we have that people either enjoy watching or have a connection to, the more people will invest time, energy and (hopefully) money into the game.
P.S., I disagree with the view that Origin is stale - I would have bought that mid-way through the QLD dynasty. But, by way of a one-game example, tell me Game III this year wasn't a great advertisement for the game (head clashes aside