Hi, I'm a professional highway engineer. I don't know how you can get so excited about a ... joke of an interstate highway, which is what I-275 is, and pathetically it is the only freeway in Pinellas County! (I-175 and I-375 are simply glorified feeder ramps and do not deserve to have their own route number).
By the way, a ramp is a short one- or two-lane low speed road that connects a street or highway to or from an interstate highway in a safe manner. Interstates 375 and 175 have their own exit and entrance ramps just like Interstate 275: Interstate 375 at Martin Luther King St N, 8 St N (entrance only), 4 Av N and 5 Av N just before 5 St N (eastern terminus) and Interstate 175 at Martin Luther King St S and 6 St S (westbound entrance and eastbound exit only) as well as 5 Av S (eastbound terminus exit only) and 4 St S (westbound entrance). But the mainline of both Interstates 375 and 175 are identical to the mainline of Interstate 275 for the two feeders' entire length.
And fifth, southern Pinellas was the only part of Pinellas County to have the totally controlled access freeway, which we know today as Interstate 275. Back in the 1960's and early to mid-1970's Clearwater and northern Pinellas County was not as developed as it is today. In other words, interstate highway service into Clearwater back then was not justified. But contrast this to the Clearwater and northern Pinellas County as we know today: That was a big mistake.
However, with the conversion of US 19 in Clearwater and northern Pinellas County to an interstate-like highway I would advocate a connection to Interstate 275, starting south on US 19 around Palm Harbor and routing it all the way to just north of Park/Gandy Blvd. (FL 694). Then have the new highway turn east and follow an upgraded version of Gandy Blvd. passing Interstate 275 (which would have a reconfigured interchange) to Tampa, connecting it at the Crosstown Expressway. Besides, an upgraded Gandy would be a beneficial hurricane evacuation route. We could call this highway Interstate 875 and I have an idea for a Gandy makeover and Interstate 875 here at Interstate275Florida.com simply by clicking here.