Many clubs would be in to sign them. Every club outside the top 6 if they could afford their wages. I expect the likes of Everton and, yes, Spurs would take interest, too. Arsenal's interest in Smalling and Jones is already well established, but carry on.
We've played a back four twice since May. Our most reliable full back - this is where dickheads pretend that Shaw hasn't been reliable elsewhere - has yet to play a competitive game for the club, and our other regular full back has just played his second game since March. Our new centre back has yet to actually play a game in that position and our other central defenders, all of whom have irrefutable experience of dealing competently with a variety of attackers in the division, have suffered from injury all throughout pre-season and the opening few games. Then there was the dalliance with the 352, which has already been shafted.
We need to some consistency at the back, and it will take some time. But yes, conceding 5 against Leicester is an anomaly. Blackett isn't ready for first team football at this level and Rojo had a very bad game in his first away game. The team collectively lost their heads from a comfortable position and I don't expect to see anything like that happen again.
I'm extremely confident that our full backs are set. They have proven more than good enough to play at this level. Rojo, I don't know much about, so we'll have to see. As for the others, with fitness and a run of games I am confident they will do well, as they have done in the past. Defending is more to do with set up as it is the individual qualities of the defenders. I stressed so in another thread recently but Gary Cahill's improvement under Mourinho and Crystal Palace under Pulis are just specific examples of this.
Believe what you want lad. I'll be right in time.