To a degree.
At level 7, you've got spell combat, spell recall, knowledge pool and magus arcanas. After that, you mostly get improvements and refinements to already existing abilities. If you go for High-BaB and spellcasting.improving classes from there on, you should still be fundamentally a Magus, albeit with a different focus.
Unlike, if you got for some kind of sneak attack build from there, or get into divine spells and go Mystic Theurge or something. That really takes you out of how a Magus plays, I think.
Anyway, in case you want to add a 3.P section:
2 levels of Wyrm Wizard after level 15 should let you Spell Combat with Harm.
1 level of Mage of the Arcane Order gives you Spellpool access to all wizard spells of level 1-3. 4 levels gives you access to all Wizard Spells of level 1-6. Magus 16, MotAO 4 gives up counterstrike, true magus, and the greater spell access in exchange for all wizard spells of level 1-6 on call. Also good for the Eldrich Scion archetype.
Magus 13/Initiate of the Sevenfold Veil 7 can be pretty solid.