In my experience, this can go either way, but judging on how things have gone over the past few years, I'm leaning more towards this not being a good move. LL owning and maintaining all their own products and processes was the best option. It's one of the reasons they bought CasperTech. It's easier to have and maintain processes like this in house than to outsource it. The same went for Tilia. Now all their payments are going to end up going through a third party where they went through their own house prior to this. If you think that Thune is in the game to make friends instead of profits, I have a bridge to Hawaii to sell you. Corporations exist to maximise their profits at the best margins possible. Thune isn't going to care about what is best for people in a game so long as the cash comes flowing in.
Here's the worst part: they are after the payment process portal to use in the US. They likely couldn't care less about Second Life. They can now use this software for anything else they want in order to compete with companies like Stripe, Square and Paypal for international commerce. I 100% won't be surprised if once the 5 year contract is up, they raise rates beyond belief on players simply so they have a reason to escape the Second Life market because of how little revenue it will generate for them and shift their focus completely to other business.
As much as I'd love to believe this was a way for LL to refocus on the game itself, it's really not. This should have stayed in house because it meant that LL would have had control of their own markets and been player focused because the exchange is what will determine the survival of the game long term. If prices to buy and sell L's goes up, you're going to see less people spending money and less new people joining. Now that a third party is involved, it's just another link in the chain that wants a piece of the pie.