We can all agree that Marvel Snap needs other ways to unlock new cards apart from its already existing, rather randomized system. Luckily, the devs feel the same way, announcing that a welcome addition to the game will be implemented "very soon."
The current version of Marvel Snap that you play most of your free time nowadays has pretty limited options regarding new unlocks, giving out one random card periodically as you progress through the Collection Level Track by upgrading your existing cards. The system can be frustrating for those players who seek the particular card to complete their dream deck, but the good news is, the solution to this problem is already on its way.
Discussing what lies ahead for Marvel Snap on the game's official discord channel (summarized by Redditor CanadianAlfredo here), the team confirmed that big changes to the game will be introduced in future updates, including collector tokens. This is a new currency that players will obtain in collector caches instead of random boosters for certain cards you usually get today.
The collector tokens will allow you to unlock cards you do not own via the game's shop. Every three hours the shop will offer one new card you can purchase. What's even better is that players who don't possess enough currency yet will be able to freeze a card they needed the most upon seeing it, to collect enough tokens and get it later. In the creators' words, this will make the collection process more fun so you can target cards you really want for decks you have in mind. Unfortunately, it sounds like you won't get tokens for the already opened caches, and shouldn't either save them now to open later for additional rewards.
According to the Marvel Snap team, tokens will be coming to the game "very soon." As of now, the devs stick to at least one big update per month, so we can expect another big patch coming in November, if everything goes according to plan. Alongside collector tokens, at least one new card will be added to the game every week.
For now, it is not guaranteed that collector tokens will be introduced in the nearest patch, but hopefully, we can expect them to arrive before the end of the year.