I imagine a lot of this really hinges on getting Walsh back, which is unlikely. If we don't get Walsh back as expected, then who becomes our long term 1? If it is Cobbo, you could put him at centre next year and then use a stop gap again while Mariner gets up to speed and hope Cobbo can then transition to fullback some time next year.
I actually think getting Walsh back while unlikely, is theoretically possible if we're clever about it. If the Warriors still want Arthars, we could use releasing him as a sweetener. And I think Lodge is opting out of there as well. So we do have the option of offering up one of our depth/bench/ development props if one of ours was looking for a
opportunity and was willing to go as well, if it came down to it. But i couldn't see the club doing something that extreme unless it was guaranteed to get Walsh over the line.
As for the long term 1, it's too early to call on it. Martin is a handy option to have, as it means we could prioritise trying to get one without going all out on both. Martin played 6 in the 2017 Cowboys GF team, so it's not like he's just a depth option, he does have experience in a finals team. So he could be the player we need at 6.
But if we miss out on Walsh and get Munster, Martin could just as easily retain the 1 jersey without the team losing too much. As much as this won't be popular, none of us here can rule Niu completely out of being in the spine line-up somewhere either. There was a reason the club had him at fullback. So that comes into it as well, depending on how he comes back from injury.
As for Cobbo, if Kevie an co. see him as a fullback long term, our left centre spot is about defence and setting up the winger from what I've seen with Bird, Boyd and Reed in the past. So it may not be the worst place for him. But I'd wait until next pre season to make that switch unless everything implodes during the current season.