Will they be replaced with 89XX and 99XX phones?
79x2 and 79x5 remain an active part of Cisco's endpoint portfolio and continue to be available for purchase. Of the more recently introduced portfolios, 69xx would be the most closely aligned to the x2 portfolio (at lower cost) and 89xx for the x5's. For your planning, if video or color displays are part of you delivery plans - adopting the 89xx with video integration (such as the 8941 and 8945's offer) will save you money vs. 79x's with Cisco Unified Video Advantage for example. 69xx (all but the 6901) can support video (does require CUVA) but the combination would be lower cost solution, if you don't need color displays, then the 79x2 portfolio.
In the long term, would the above portfolios be likely to replace the 79x2 and 79x5 - most likely, yes. These decisions are evaluated and made by the BU based on market uptake to these new portfolios and if they are fufilling the needs of our customers. So don't have a timeframe for you at this point. What can confirm is that Cisco remains committed to offering a comprehensive endpoint portfolio to support a variety of user's need and any such EOS/EOL decisions will be driven with that in mind.
hope this helps.
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