Speculation is building that Minneapolis-based Medtronic ($MDT) will modify its offer for Dublin-based Covidien ($COV). This notion comes on the heels of Walgreens ($WAG) deciding not to follow a similar tax-inversion strategy with its Alliance Boots deal earlier this month. This fallout, triggered by U.S. government and public pushback, makes inversion a riskier venture, said MKM Holdings strategist Jim Strugger. Shareholders aren't convinced entirely that the deal will close; Covidien shares closed yesterday at $87.26 while Medtronic's offer values each at $96.12, representing a disparity of nearly 10%. Covidien spokesperson Peter Lucht declined comment saying the $42.9 billion transaction should close as planned. More