Whether you (a) drop land-line service and change to cellular-only, and (b) port a land-line number to keep it (not clear on which question you mean to ask) depends on a number of personal circumstances and preferences.
I went cell-only some time ago (2010 I think) and have never felt the need to get land-line service. I kept a number I liked for a long time, porting from one carrier to another, mainly out of worry people who had my number would lose contact. Last year I decided to get a new number that reflects my actual location, but I kept my old number for a while while friends and family and professional contacts transitioned. I actually had no problem changing over, after a few weeks the old number stopped ringing so I canceled it.
Besides letting your contacts know about a phone number change there’s the bigger hassle of updating online services that use phone numbers for verification and authentication. If you’re not careful you can lock yourself out of online accounts. For that reason it may be safer to port a number or keep an old number active for a while.
I traveled and lived overseas for six years, usually getting a local SIM card and number everywhere I stayed for more than a few days. I ported my US number to Google Fi to maintain contact with family and customers. A dual-SIM phone is handy for doing that.