They will implement 10% tithing or a lesser amount based on ability, it's coming. They will set up a system where you can only contribute through a debit or credit card. If you must donate in cash they will inquire 'why not just deposit and use debit instead'. If you insist in cash they will want you to hand it to them so they can give you a receipt, they will eventually remove all donation boxes and push for automatic monthly payments set up through your bank, this way they can track who's tithing and who's not. Obviously they will not admit they want to track contributions they will allude to some accounting simplicity reason. They might leave a box for the new ones and visitors but they will ask baptized members to follow direction in this loving provision.
Checks are a thing of the past they will accept them and work's for tracking purposes, but with all the fraud happening they will have a local needs explaining why its better to just do debit or credit it's safer, more convenient and some level of bank protection if their is fraud. They will also explain that the money will be transferred almost immediately unlike checks their is sometime as much as 5-7 day waiting period.
Time's are changing everything is going electronic transfer and banking, I no longer write out checks its 99% electronic banking for us and my business.
I don't believe it will be a disfellowshiping offense but it will mark the one's not contributing as week or dissenting from the flock. If this seems unlikely remember what you thought about the internet and TV evangelism.