Following Sprint’s confirmation that it has chosen not to move forward in releasing a 4G WiMAX-enabled version of RIM’s BlackBerry PlayBook tablet, RIM said it has decided to focus instead on LTE. “RIM has decided to prioritize and focus its 4G development resources on LTE,” RIM said in an emailed statement on Friday. “We remain excited and committed to delivering innovative and powerful 4G tablets to the US market together with our carrier partners. Testing of BlackBerry 4G PlayBook models is already underway and we plan to enter labs for network certifications in the US and other international markets this fall.”