Hi there, thanks for asking and I'm glad you like the asset pack! The answer is YES, there will be future pixel particle effect packs, but it might be a while. I'm actually working on a tool right now that can be used to create your own effects like this!
Here's a couple examples of what it'll be able to do:
Of the above GIFs, only the tornado is using an external asset (a 4-frame wind spiral animation). The others are just using basic shape particles.
If you hit the follow button on my page on itch.io (or if you're already following) you'll be notified when it's released! It still needs a lot of tweaking and some core features, but... maybe late 2020?