You suppose that by waiting as the IDF has....and Hamas continuing to launch rockets willy nilly.....that at some point that could lead to the rocket firing coming to a natural end by Hamas totally expending its ready supply and they will be forced to either smuggle in new armament or put their manufacturing cells into max rate production and making themselves more susceptible to interdiction by the IDF? If the IDF enters Gaza by ground it will be tasked based upon current and newly acquired intelligence of where the building of weapons inside Gaza are taking place and also by tracing back the launch and traffic to/from those sites.
That puts Hamas in a bind.....if they run out of rockets.....cannot smuggle rockets into Gaza....and their manufacturing cells are overrun by the IDF....then Hamas has to revert to a different mode of fighting.
With a highly secure border between Gaza and Israel.....and the West Bank and Israel.....what will Hamas do?
To be honest....the rocket attacks do not seem to have had a significant effect upon Israel despite the many that have been launched.
The IronDome and other counter-measures seem to be stopping many of the Hamas rockets without them reaching the ground intact.
Any thinking the IDF is just going to do a complete razing. of northern Gaza just is not taking into consideration it is not needed and would only bring such political pressure form around the World as to make it a very unwise action.
The Israeli's might be in a mood to wreak havoc on those that attacked them but it will be done with some very careful calculations as to what they can do in reality.
I am sure they have a target list that varies with the situation to include locations inside Gaza that are known Hamas sites of all sorts.....and those are on the top of the list.
The thing about tunnels is they have two ends or more....find one opening and you can find the rest from inside rather than looking from outside.