Would they keep using 8AR-FTS for new TNGA vehicles launched after 2019? Surely it will live on some legacy models, but I doubt the IS will be using it. An IS300 would not go low enough in China (IS260 is a more appropriate entry-level model), nor high enough in US (competition will move to the 200kW/280hp class which is better covered by the 2.5T).
I feel the hybrid system between the 300h and 500h is the 450h. The FKS-based 2.5 hybrid with high output battery (for the time being let's call it 350h) that could appear on the Highlander should be considered a variant of the 300h. The 450h could be a turbo hybrid utilizing either 2.0T or 2.5T ICE. Offering a 350h and 450h is consistent with their twin hybrid strategy. A more affordable RX350h is something they certainly need in Europe.
Going back to the IS, I doubt EU will care about the 300h losing 13hp if price is reduced (and actual power at the wheels should be comparable due to efficiency improvements). Then a 450h in the 225-250kW class could be the flagship non-F model, should they not choose to do an F-lite/F strategy.
Like the 8AR-FTS, the 2GR-FKS will be near EOL in 2019 and should only be used on legacy models. Launching yet another IS350 with 310hp is asking for embarrassment.
- 2.5t is replacement for 3.5 V6... it is not going to happen in US where people prefer V6. 2.5t is likely more expensive to produce too.
- 2.0t as base, sure... they will use that engine for quite a while... just improve it and it will likely be much better fit for TNGA than old platform.
- 300h will not lose 13hp in EU... it will simply have different tuning for RWD with more hp, look below.
- IS300h had 181hp from engine, NX300h has 155hp from engine, Camry has 176hp from engine. So 5+ hp extra from exhaust, etc, then 5hp extra in battery power will bring us to more than IS300h. But this is not enough for Highlander and RX. What they could possibly do is use non-atkinson version of engine, like old GS450h for instance, from Camry - so 205hp + 45hp from battery output and thats 250hp... pretty reasonable for Highlander! It can still go into atkinson cycle like Camry engine, just not all the time. It will still be very efficient compared to 450h engine.
Neither 8AR nor 2GR will reach AOL in next 5 years or so.
Lots of manufacturers like Volvo are saying how these are their last generation engines btw.