I thought the point was to increase the block size limit to avoid having to use off chain transactions.
The block size limit should raised because off-chain transaction systems should not be artificially subsided.
If the limit is not raised, the more transactions will be pushed off chain which otherwise belong on the chain, which won't exactly kill the entire space right away, but as a plan B it's far inferior to allowing the distribution of on-chain vs off-chain transactions to find a natural balance.
I don't even think transactions will be pushed off-chain anymore than what is happening organically today. Yes, it is good that off-chain solutions develop, but they should attract user business on their own merits, not be a refuge for users who are forced there. Forcing users to do something stretches the network effect to its limits. Users will instead transact with a different cryptocurrency, and Bitcoin will hemorrhage market share.