Block size increase in itself is not going to increase the number of TPS because of the orphan risk.
To compete on a global scale with just Paypal f.i., bitcoin would need to go from 7 TPS to something like 700 TPS, or 100 MB block size, at which point propagation becomes problematic, and the risk of a block getting orphaned would be very high.
We already see many blocks that are not full, even blocks with just 1 tx or a couple hundred tx.
One way to reduce the orphan block risk could be to allow 1-block fork merging: a block could be allowed to have multiple previous blocks. This way if two blocks come at the same time, rather than one orphaning the other, the next block could accept both.
This sounds a lot like
GHOST ...
Currently if block B & C are mined based on block A, then only B or C will be accepted by block D being mined on either B or C.
The proposal would be that D could accept both B & C, half the B & C rewards would be lost (so the total reward is unchanged), duplicate transactions in a merge would be ignored/pruned. And probably that part of B & C reward+fee could go to D, to incentivize the merging.
... and
DECOR.