Since SB already controls Clearwire’s business as in "prospective de jure" so why would SB waste their money and buy Clearwire’s shares? I think SB will buy Clearwire’s debt instead which is tied to its spectrum.
Control doesn't equal ownership. Without 100% ownership there will be network management problems. Also Access to Spectrum isn't free. S pays $550M a year to CLWR for access even though S owns half the spectrum. It would $1.1 BILLION a year if they owned none of CLWR. Demand is going up and the amount Sb and S have to pay is going to go up. Why pee money away on that. After 10 years of this, they could have bought the spectrum and saved Billions.
What you're saying isn't true. In order to avoid a conflict of interest and for Clearwire to perform its fiduciary duty to shareholders, Sprint has the pay the same for the access as they would if they owned 0% of Clearwire. This increases the value of Clearwire (aka share price) which benefits shareholders. They are theoretically "rewarded" through share price, but cannot be given any non-competitive discount.
Your guess makes sense: I don't see much reason to acquire much more... maybe some just to make their rights clear. Sprint has made overtures to existing stake holders who reported turned down the offer. However, S-SB will likely keep that offer on the shelf and might pick up some in the open market. There is not much rationale for doing that other than legal and positioning clarity.
I agree that the debt is where SB will concentrate: it would be such an obvious benefit to clear out that high interest rate junk bond status quagmire. The debt can be viewed as the cost of the spectrum plus come ongoing operational network assets... its best to convert that to internally funded debt or run it back out as restructured debt instruments under the new company. SB-S should be able to secure future debt at competitive rates.